Download Seagate Barracuda 180 Family Product manual

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Barracuda 1 and 2 Disc Drive
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ST11950N/ND, ST11950W/WD
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ST12550N/ND, ST12550W/WD
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Product Manual, Volume 1
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Barracuda 1 and 2 Disc Drive
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ST11950N/ND, ST11950W/WD,
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ST12550N/ND, ST12550W/WD
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Product Manual, Volume 1
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© 1994 Seagate Technology, Inc. All rights reserved
Publication number: 83327780, Rev. C
November 1994
Seagate® , Seagate Technology®, and the Seagate logo are registered
trademarks of Seagate Technology, Inc. Barracuda™ is a trademark of
Seagate Technology, Inc. Other product names are registered trademarks
or trademarks of their owners.
Seagate reserves the right to change, without notice, product offerings or
specifications. No part of this publication may be reproduced in any form
without written permission from Seagate Technology, Inc.
Revision status summary sheet
Revision
Date
Writer/Engineer
Sheets
Affected
A (preliminary-01)
A (preliminary-02)
A (preliminary-03)
A
B (preliminary-01)
B
C (draft)
C
04/05/93
04/20/93
05/01/93
05/11/93
09/15/93
10/18/93
10/11/94
11/04/94
L. Newman/J. Olson
L. Newman/J. Olson
L. Newman/J. Olson
L. Newman/J. Olson
L. Newman/J. Olson
L. Newman/J. Olson
L. Newman/J. Olson
L. Newman/J. Olson
All
All
All
All
All
All
All
All
Note. Product Manual 83327780 is Volume 1 of a two-volume
document with the SCSI interface information in the Volume 2
SCSI-2 Interface Product Manual, part number 77738479.
Barracuda 1 and 2 Product Manual, Rev. C
v
Contents
1.0 Scope .................................................................................................................................
1
2.0 Applicable standard and reference documentation .......................................................
3
2.1 Standards .....................................................................................................................
3
2.2 Applicable reference documents ...................................................................................
3
3.0 General description ...........................................................................................................
5
4.0 Standard features ..............................................................................................................
7
4.1 Performance .................................................................................................................
7
4.1.1 Reliability .............................................................................................................
7
4.2 Unformatted and formatted capacities ..........................................................................
8
4.3 Options .........................................................................................................................
8
4.4 Installation .....................................................................................................................
9
5.0 Performance characteristics ............................................................................................ 11
5.1 Internal drive characteristics ......................................................................................... 11
5.2 SCSI seek performance characteristics ........................................................................ 11
5.2.1 Seek time ............................................................................................................ 13
5.2.2 Format drive command execution time ................................................................ 13
5.3 General performance characteristics ............................................................................ 14
5.4 Start/stop time ............................................................................................................... 14
5.5 Prefetch/multi-segmented cache control ....................................................................... 15
5.5.1 Adaptive read lookahead ..................................................................................... 16
5.6 Caching write data ........................................................................................................ 16
5.7 Synchronized spindle operation .................................................................................... 17
6.0 Reliability specifications ................................................................................................... 21
6.1 Error rates ..................................................................................................................... 21
6.1.1 Environmental interference.................................................................................. 21
6.1.2 Write errors ......................................................................................................... 21
6.1.3 Seek errors ......................................................................................................... 22
6.2 Reliability and service ................................................................................................... 22
6.2.1 Mean time between failures (MTBF).................................................................... 22
6.2.2 Air flow ................................................................................................................ 22
6.2.3 Preventive maintenance ...................................................................................... 28
6.2.4 Service life........................................................................................................... 28
6.2.5 Service philosophy .............................................................................................. 28
6.2.6 Installation ........................................................................................................... 28
6.2.7 Service tools........................................................................................................ 28
6.2.8 Hot plugging Barracuda 1 and 2 disc drives ........................................................ 28
vi
7.0
Barracuda 1 and 2 Product Manual, Rev. C
Physical/electrical specifications ................................................................................... 31
7.1
AC power requirements ............................................................................................ 31
7.2
DC power requirements ............................................................................................ 31
7.2.1 Conducted noise immunity ............................................................................ 33
7.2.2 Power sequencing ......................................................................................... 33
7.2.3 12V current profile ......................................................................................... 34
7.3
Heat/power dissipation .............................................................................................. 35
7.4
Environmental limits .................................................................................................. 35
7.4.1 Temperature .................................................................................................. 35
7.4.2 Relative humidity ........................................................................................... 35
7.4.3 Effective altitude (sea level) ........................................................................... 36
7.4.4 Shock and vibration ....................................................................................... 36
7.4.5 Air cleanliness ............................................................................................... 37
7.4.6 Acoustics ....................................................................................................... 37
7.5
Electromagnetic compatibility .................................................................................... 37
7.6
Mechanical specifications ......................................................................................... 38
7.6.1 Drive orientation ............................................................................................ 40
7.6.2 Cooling .......................................................................................................... 40
8.0
Media characteristics ...................................................................................................... 41
8.1
9.0
Media description ...................................................................................................... 41
Defect and error management ........................................................................................ 43
9.1
Defects and errors .................................................................................................... 43
10.0 Option/configuration headers ......................................................................................... 45
10.1 Drive ID/option select headers .................................................................................. 45
10.1.1 ST11950N/ND and ST12550N/ND configuration ........................................... 45
10.1.2 ST11950W/WD and ST12550W/WD configuration ........................................ 48
10.2 Synchronized spindles interface ............................................................................... 50
10.2.1 Electrical description ...................................................................................... 50
10.3 Grounding ................................................................................................................. 52
11.0 Interface requirements .................................................................................................... 53
11.1 General description ................................................................................................... 53
11.2 SCSI interface messages supported ......................................................................... 53
11.3 SCSI interface commands supported ........................................................................ 54
11.3.1 Inquiry data .................................................................................................... 56
11.3.2 Mode sense data ........................................................................................... 56
11.4 SCSI bus conditions and miscellaneous features supported ..................................... 61
11.5 Synchronous data transfer ........................................................................................ 62
Barracuda 1 and 2 Product Manual, Rev. C
vii
11.5.1 Synchronous data transfer periods supported .............................................. 62
11.5.2 REQ/ACK offset ............................................................................................ 63
11.6 DC cable and connector ........................................................................................... 63
11.7 SCSI physical interface ............................................................................................. 63
11.7.1 Physical characteristics ................................................................................ 64
11.7.2 Connector requirements ............................................................................... 65
11.7.3 Electrical description ..................................................................................... 66
11.8 SCSI non-wide physical interface ............................................................................. 70
11.9 SCSI wide physical interface ..................................................................................... 73
11.10 Disc drive SCSI timing .............................................................................................. 76
Index .......................................................................................................................................... 79
Figures
1
Barracuda 1 and 2 family disc drives ................................................................................ 1
2
Barracuda disc drive (exploded view) ............................................................................... 5
3
OEM interruptible thermal compensation implementation ................................................. 12
4
Synchronized drive interconnect diagram ......................................................................... 17
5
Synchronized reference signal characteristics .................................................................. 18
6
Air-flow pattern .................................................................................................................. 23
7
TYFX temperature measurement locations ....................................................................... 24
8
UYFX temperature measurement locations ...................................................................... 25
9
TYGX temperature measurement locations ...................................................................... 26
10
PYGX temperature measurement locations ...................................................................... 27
11
Temperature measurement location ................................................................................. 27
12
Barracuda 1 and 2 drives typical +12V current profiles ..................................................... 34
13
Mounting configuration dimensions for N/ND drives .......................................................... 38
14
Mounting configuration dimensions for W/WD drives ........................................................ 39
15
Recommended mounting .................................................................................................. 40
16
ST11950N/ND and ST12550N/ND physical interface ....................................................... 45
17
ST11950N/ND and ST12550N/ND jumper connectors ..................................................... 46
18
ST11950W/WD and ST12550W/WD physical interface .................................................... 48
19
ST11950W/WD and ST12550W/WD jumper connectors .................................................. 48
20
SCSI reference index signal driver/receiver combination .................................................. 50
21
ST11950N/ND and ST12550N/ND configuration select header specification.................... 51
22
ST11950W/WD and ST12550W/WD configuration select header specification ................ 51
23
ST11950N/ND and ST12550N/ND physical interface ....................................................... 63
24
ST11950W/WD and ST12550W/WD physical interface .................................................... 64
viii
Barracuda 1 and 2 Product Manual, Rev. C
25
Single-ended transmitters and receivers ........................................................................... 67
26
Typical differential I/O line transmitters/receivers and terminators .................................... 68
27
Non-shielded SCSI device connector................................................................................ 70
28
Wide SCSI device connector ............................................................................................ 73
Tables
1
DC power requirements for ST11950N/ND and ST12550N/ND drives ............................. 31
2
DC power requirements for ST11950W/WD and ST12550W/WD drives .......................... 32
3
SCSI messages supported ............................................................................................... 53
4
Supported commands ....................................................................................................... 54
5
Barracuda 1 and 2 family drive inquiry data ...................................................................... 56
6
Mode Sense data, ST11950 default values (SCSI-1 implementation) ............................... 57
7
Mode Sense data, ST11950 default values (SCSI-2 implementation) ............................... 58
8
Mode Sense data, ST12550 default values (SCSI-1 implementation) ............................... 59
9
Mode Sense data, ST12550 default values (SCSI-2 implementation) ............................... 60
10
SCSI bus conditions and other miscellaneous features .................................................... 61
11
Synchronous data transfer periods for ST11950N/ND and ST12550N/ND drives ............. 62
12
Synchronous data transfer periods for ST11950W/WD and ST12550W/WD drives .......... 62
13
Single-ended cable pin assignments (non-shielded connector)
for ST11950N and ST12550N drives ................................................................................ 71
14
Differential cable pin assignments (non-shielded connector)
for ST11950ND and ST12550ND drives ........................................................................... 72
15
Single-ended contact assignments (P cable) for ST11950W and ST12550W drives ........ 74
16
Single-ended contact assignments (P cable) for ST11950WD and ST12550WD drives ... 75
17
Disc drive SCSI timing ...................................................................................................... 76
Barracuda 1 and 2 Product Manual, Rev. C
1.0
1
Scope
This manual describes Seagate Technology®, Inc. Barracuda™ 1 and 2
disc drives.
Barracuda drives support the small computer system interface-2 (SCSI-2)
as described in the ANSI SCSI and SCSI-2 interface specifications to the
extent described in this manual. The SCSI-2 Interface Product Manual
(part number 77738479) describes general SCSI interface characteristics
of this and other families of Seagate drives.
ST11950N/ND and ST11950W/WD drives are classified as Barracuda 1
family drives. ST12550N/ND and ST12550W/WD drives are classified as
Barracuda 2 family drives.
N/ND type
W/WD type
Figure 1. Barracuda 1 and 2 family disc drives
2
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
2.0
3
Applicable standard and
reference documentation
Seagate takes all reasonable steps to ensure that its products are certifiable
to currently accepted standards. Typical applications of these disc drives
include customer packaging and subsystem design.
Safety agencies conditionally certify component assemblies, such as the
Barracuda disc drive, based on their final acceptability in the end-use
product. The subsystem designer is responsible for meeting these conditions of acceptability in obtaining safety/regulatory agency compliance in
their end-use product and certifying where required by law.
2.1
Standards
The Barracuda disc drive is a UL recognized component per UL1950, CSA
certified to CSA C22.2 No. 950-M89, and VDE certified to VDE 0805 and
EN60950.
The Barracuda disc drive is supplied as a component part. It is the responsibility of the subsystem designer to meet EMC/regulatory requirements.
Engineering test characterizations of radiated emissions are available from
the Seagate safety department.
2.2
Applicable reference documents
Barracuda Disc Drive Installation Guide
Seagate part number: 83327770
SCSI-2 Interface Product Manual (volume 2)
Seagate part number: 77738479
ANSI small computer system interface (SCSI) documents
ANSI X3.131-1986
(SCSI-1)
X3T9.2/86-109 Rev. 10H (SCSI-2)
X3T9.2/91-010 Rev. 10 (SCSI-3) Parallel Interface
In case of conflict between this document and any referenced document, this
document takes precedence.
4
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
3.0
5
General description
Barracuda drives are low-cost, high-performance, random-access storage
devices designed to meet the needs of the original equipment manufacturer
(OEM) marketplace.
The Barracuda drive’s interface supports multiple initiators, disconnect/
reconnect, self-configuring host software, and automatic features that relieve the host from knowing the physical characteristics of the targets (logical
block addressing is used).
The head and disc assembly (HDA) is sealed at the factory. Air circulates
within the HDA through a non-replaceable filter to maintain a contaminationfree HDA environment.
Refer to Figure 2 for an exploded view of the drive. This exploded view is for
information only—never disassemble the HDA and do not attempt to service
items in the sealed enclosure (heads, media, actuator, etc.) as this requires
special facilities. The drive contains no replaceable parts. Opening the HDA
voids your warranty.
Figure 2. Barracuda disc drive (exploded view)
6
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda drives use a dedicated landing zone at the innermost radius of the
media to eliminate the possibility of destroying or degrading data by landing
in the data zone. The drive automatically goes to the landing zone when the
power is removed.
An automatic shipping lock prevents potential damage to the heads and
discs. The shipping lock disengages when power is applied to the drive and
the head load process begins.
Barracuda drives decode track 0 location data from the dedicated servo
surface to eliminate mechanical transducer adjustments and related reliability concerns.
A high-performance actuator assembly with a low-inertia, balanced, patented, straight-arm design provides excellent performance with minimal
power dissipation.
Barracuda 1 and 2 Product Manual, Rev. C
4.0
Standard features
Barracuda 1 and 2 drives have the following standard features:
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4.1
Performance
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4.1.1
Integrated SCSI controller
Single-ended or differential SCSI drivers and receivers
Asynchronous and synchronous data-transfer protocols
Firmware downloadable using a SCSI interface
Selectable sector size from 180 to 4,096 bytes per sector
Programmable sector-reallocation scheme
Flawed sector reallocation at format time
Programmable auto-write and auto-read reallocation
Reallocation of defects on command (post format)
96-bit Reed-Solomon error-correction code
Sealed head and disc assembly (HDA)
No preventive maintenance or adjustments required
Dedicated head-landing zone
Automatic shipping lock
Automatic thermal compensation
Embedded Grey Code track address to eliminate seek errors
Self-diagnostics performed at power-on
1:1 interleave
Zone bit recording (ZBR)
Vertical, horizontal, or top-down mounting
Dynamic spindle brake
Active termination with removable terminator modules
Synchronous spindle capability
1,024 Kbyte data buffer (N/ND/W models)
512 Kbyte data buffer (WD models)
Low audible noise for office environment
Low power consumption
Programmable multi-segmentable cache buffer
7,200 RPM spindle; average latency = 4.17 msec
Command queuing of up to 64 commands
Background processing of queue
Supports start and stop commands
Provides synchronized spindle capability
Adaptive seek velocity; improved seek performance
Reliability
• 500,000 hour MTBF
• LSI circuitry
• Balanced low-mass rotary voice-coil actuator
7
8
4.2
Barracuda 1 and 2 Product Manual, Rev. C
Unformatted and formatted capacities
Standard OEM models are formatted to have 512-byte sectors.
The ST11950 drive has six (6) spare sectors per cylinder and one (1) spare
cylinder per unit.
The ST12550 drive has nine (9) spare sectors per cylinder and one (1) spare
cylinder per unit.
Formatted
Unformatted
ST11950N/ND
ST11950W/WD
ST12550N/ND
ST12550W/WD
1,690 Mbytes
1,690 Mbytes
2,139 Mbytes
2,139 Mbytes
2,030 Mbytes
2,030 Mbytes
2,572 Mbytes
2,572 Mbytes
Users having the necessary equipment may modify the data block size
before issuing a format command to obtain different formatted capacities.
User-available capacity also depends on the spare reallocation scheme
selected. See the Mode Select command and the Format command in the
SCSI-2 Interface Product Manual (part number 77738479).
4.3
Options
The capacities shown in Section 4.2 are normally provided. Other capacities can be ordered depending on the sparing scheme and sector size
requested.
The following options are incorporated at the time of production or are
available separately.
• Front panel (green lens), part number 70869751
The standard front panel is black plastic. You may order other colors. Each
panel has a single rectangular green LED indicator lens that, when
glowing, indicates the drive is selected.
• Barracuda Disc Drive Installation Guide, part number 83327770
This manual provides basic installation information for persons not
familiar with the product. It also includes information on obtaining technical support and service for the drive.
• Drive termination for single-ended drives
Removable resistor modules (SIPs) provide ST11950N and ST12550N
drive termination. Permanently mounted active terminator ICs provide
ST11950W and ST12550W drive termination; however, the ICs may be
disabled by removing the Enable Drive Terminator jumper from J4 pins 11
and 12. See Section 11.7.3.3.
• Single-unit shipping pack kit
The drive is shipped in bulk packaging to provide maximum protection
against transit damage. Units shipped individually require additional
protection as provided by the single-unit shipping pack.
• Adapter accessory frame kit, part number 75790701
This kit contains a frame, which allows a 3.5-inch drive to be mounted
in a 5.25-inch drive bay. It includes mounting hardware, front panel with
a green lens, an LED with cable that connects to the remote LED
connector, and installation instructions.
Barracuda 1 and 2 Product Manual, Rev. C
4.4
9
Installation
For option jumper locations and definitions refer to Section 10.1. Drive default
mode parameters are not normally needed for installation. Refer to
Section 11.3.2 for default mode parameters if you need them.
• Ensure that the SCSI ID of the drive is not the same as the host adapter.
• If multiple devices are on the bus, set the drive’s SCSI ID to one that is not
presently used by other devices on the bus.
• If the drive is the only device on the bus, attach it to the end of the SCSI
bus cable. Internal termination is available on ST11950N, ST11950W,
ST12550N, and ST12550W drives (see Sections 10.1 and 11.7.3.4).
External terminators are required for ST11950ND, ST11950WD,
ST12550ND, and ST12550WD drives. These external terminators must
be provided by the user, systems integrator, or host equipment manufacturer.
• If you attach the drive to a bus that contains other devices, and the new
drive is not attached to the end of the bus, remove termination from the new
drive.
• Set all appropriate option jumpers prior to applying power to the drive. If
you change jumpers after applying power, recycle the drive’s power to
make the new settings effective.
Formatting
• It is not necessary to low-level format this drive. The drive is shipped from
the factory low-level formatted in 512-byte sectors.
• Reformat the drive if:
a. You select a different sector size.
b. You select a different spare-sector allocation scheme.
10
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
5.0
11
Performance characteristics
This section provides performance-related characteristics and features of
Barracuda 1 and 2 drives.
5.1
5.2
Internal drive characteristics
Drive capacity, Mbytes unformatted
ST11950
2,030
ST12550
2,572
Read/write data heads, maximum
15
19
Bytes per track, average
49,768
49,768
Bytes per surface, Mbytes unformatted
135.7
135.7
Cylinders/tracks per surface,
user accessible
2,706
2,707
Tracks per inch
3,047
3,047
Bits per inch
52,187
52,187
Servo heads
1
1
Internal data rate
Mbits/sec, variable with zone
34.3 to 56.5
34.3 to 56.5
Disc rotation speed
7,200 ± 0.5%
7,200 ± 0.5%
Average rotational latency, msec
4.17
4.17
SCSI seek performance characteristics
All performance characteristics assume that automatic adaptive thermal
compensation is not in process when the drive receives the SCSI command.
Automatic adaptive thermal compensation will not interrupt an active SCSI
command. If adaptive thermal compensation is in process when a SCSI
command is received, the command is queued until compensation
completes. When compensation completes for the head, the first queued
SCSI command executes, and the drive continues compensation for the
remaining head(s).
The above procedure continues until compensation for all heads has
completed, or until 10 minutes have elapsed. The drive initiates an automatic
adaptive thermal compensation cycle once on power-up before completing
its initialization sequence, once after 1 minute from the end of initialization,
and then once approximately every 10 minutes. Automatic thermal
compensation occurs at other times but should be transparent to the user
(e.g., during format, at Re-Zero command, at spindle-up, during read-error
recovery, and during reassign-block functions). You can use the Re-Zero
command to reset the thermal compensation timer to its start to let the host
know when the interruption for thermal compensation will occur.
Refer to Table 17 in Section 11.10 and to the SCSI-2 Interface Product
Manual (part number 77738479) for additional timing details.
12
Barracuda 1 and 2 Product Manual, Rev. C
Start
A
Has
10 min.
timer
expired?
TCAL
head
No
Yes
Has
target
received a SCSI
No
command?
Set
10 minute
timer
No
Is
SCSI
command in
progress?
Yes
Complete
Command
All
heads
calibrated?
Yes
Has
target
received a SCSI
command?
Yes
Yes
All
heads
calibrated?
Target
completes
SCSI
command
No
Select
next
head
No
No
Yes
A
Seek to
TCAL cyl
and select
next head
Seek to
TCAL cyl
and select
head zero
Figure 3. OEM interruptible thermal compensation implementation
Barracuda 1 and 2 Product Manual, Rev. C
5.2.1
13
Seek time
Average typical*
Single track typical*
Full stroke typical*
Drive level (msec)
read
write
8.0
9.0
0.6
0.9
17
19
Drive including
controller overhead
without disconnect (msec)
read
write
9.0
10.0
1.6
1.9
18.0
20.0
*Typical seek values are measured under nominal conditions of temperature, voltage, and horizontal orientation on a representative sample of
drives.
5.2.2
Format drive command execution time
for ≥ 512-byte sectors
Maximum (with verify)
Maximum (without verify)
ST11950
30 minutes
18 minutes
ST12550
37 minutes
22 minutes
14
5.3
Barracuda 1 and 2 Product Manual, Rev. C
General performance characteristics
Minimum sector interleave
1 to 1
Data buffer to/from disc media
512-byte sector
Data transfer rate (≤ 1 sector)
Minimum
Maximum
4.28 Mbytes/sec*
7.06 Mbytes/sec*
Data transfer rate (< 1 track)
Minimum
Maximum
3.56 Mbytes/sec*
5.96 Mbytes/sec*
SCSI interface data
Asynchronous transfer rate *
(maximum instantaneous)
5.0 Mbytes/sec** (non-wide)
10.0 Mbytes/sec*** (wide)
Synchronous transfer rate fast and wide
(ST11950N/ND and ST12550N/ND)
0.5 to 10 Mbytes/sec
Synchronous transfer rate wide
(ST11950W/WD and
ST12550W/WD)
5.0 to 20 Mbytes/sec
Sector sizes
Default
Variable in even-sector sizes
512-byte data blocks
180 to 4,096 bytes
Read/write consecutive sectors on a track
Yes
Flaw reallocation performance impact
Spare sectors per track reallocation
Spare sectors per cylinder reallocation
Spare tracks per volume reallocation
Negligible
Negligible
35 msec (typical)
Overhead time for head switch
0.7 msec
Overhead time for one-track cylinder switch
1.6 msec (typical)
Average rotational latency
4.17 msec
* Rate measured from the start of the first sector transfer to or from the host.
** Assumes system ability to support 5.0 Mtransfers/sec and no cable loss.
*** Assumes system ability to support 5.0 Mtransfers/sec and no cable loss.
5.4
Start/stop time
Disabling the Motor Start option causes the motor to start as soon as power
is applied, causing the drive to become ready within 30 seconds after DC
power is applied at nominal voltage. If a recoverable error condition is
detected during the start sequence, the drive executes a recovery procedure
which may cause the drive to become ready in excess of 30 seconds. During
the start sequence the drive responds to some commands over the SCSI
interface. Stop time is less than 30 seconds (maximum) from removal of DC
power.
Enabling the Motor Start option causes the internal controller to accept the
commands listed in the SCSI-2 Interface Product Manual (77738479) less
than 3 seconds after applying DC power. After receiving the Motor Start
command, the drive becomes ready for normal operation within 30 seconds
Barracuda 1 and 2 Product Manual, Rev. C
15
(excluding the error recovery procedure). The Motor Start command can
also be used to command the drive to stop the spindle (see the Start/Stop
command information in the SCSI-2 Interface Product Manual ).
There is no power control switch on the drive.
5.5
Prefetch/multi-segmented cache control
The drive provides a prefetch/multi-segmented cache algorithm, which in
many cases enhances system performance. To select this feature, the host
sends the Mode Select command with the proper values in the applicable
bytes in page 08h (see the SCSI-2 Interface Product Manual ). Default is
prefetch and cache operation enabled.
Of the 1,024 Kbytes physical buffer space in the ST11950N/ND/W and
ST12550N/ND/W drives, approximately 960 Kbytes can be used as a cache.
Of the 512 Kbytes physical buffer space in the ST11950WD and ST12550WD
drives, approximately 480 Kbytes can be used as a cache. The cache can
be divided into logical segments from which data is read and to which data
is written.
The drive keeps track of the logical block addresses of the data stored in each
segment of the cache. If the cache is enabled (see RCD bit, Table 5.2.1-27
in the SCSI-2 Interface Product Manual ), data requested by the host with a
read command is retrieved from the cache before any disc access is initiated.
Data in contiguous logical blocks immediately beyond that requested by the
Read command can be retrieved and stored in the cache for immediate
transfer to the initiator on subsequent read commands. This is referred to as
the prefetch operation. Since data that is prefetched may replace data
already in the cache segment, an initiator can limit the amount of prefetch
data to optimize system performance. The drive never prefetches more
sectors than the number specified in bytes 8 and 9 of Mode page 08h (see
the SCSI-2 Interface Product Manual ). If the cache is not enabled, 960
Kbytes of the buffer (480 Kbytes for ST11950WD and ST12550WD drives)
are used as a circular buffer for read/writes, with no prefetch operation and
no segmented cache operation.
The following is a simplified description of the prefetch/cache operation:
Case A. A read command is received and the first logical block is already in
the cache.
1. The drive transfers to the initiator the first logical block requested plus all
subsequent contiguous logical blocks that are already in the cache. This
data may be in multiple segments.
2. When a requested logical block is reached that is not in any segment,
the drive fetches it and any remaining requested logical block addresses
from the disc and puts them in a segment of the cache. The drive
transfers the remaining requested logical blocks from the cache to the
initiator in accordance with the “buffer-full” ratio specification given in
Mode Sel ect Disconnect/Reconnect parameters, page 02h (see the
SCSI-2 Interface Product Manual ).
3. The drive prefetches additional logical blocks contiguous to those
transferred in step 2 above and stores them in the segment. The drive
stops filling the segment when the maximum prefetch value has been
transferred (see the SCSI-2 Interface Product Manual ).
16
Barracuda 1 and 2 Product Manual, Rev. C
Case B. A read command is received and the first logical block address
requested is not in any segment of the cache.
1. The drive fetches the requested logical blocks from the disc and
transfers them into a segment, then from there to the initiator in
accordance with the “buffer-full” ratio specification given in Mode Select
Disconnect/Reconnect parameters, page 02h (see the SCSI-2 Interface Product Manual ).
2. The drive prefetches additional logical blocks contiguous to those transferred in Case A, step 2 above and stores them in the segment. The drive
stops filling the segment when the maximum prefetch value has been
transferred.
During a prefetch, the drive crosses a cylinder boundary to fetch data only
if the Discontinuity (DISC) bit is set to 1 in bit 4 of byte 2 of the Mode Select
parameters page 8h. Default is zero for bit 4 (see the SCSI-2 Interface
Product Manual ).
Each cache segment is actually a self-contained circular buffer whose
length is an integer number of sectors. The drive supports operation with any
integer number of segments from 1 to 16. Divide the 983,040 bytes (491,520
bytes for ST11950WD and ST12550WD drives) in the buffer by the number
of segments to get the segment size; default is 3 segments (see the SCSI2 Interface Product Manual ). The wraparound capability of the individual
segments greatly enhances the cache’s overall performance, allowing a
wide range of user-selectable configurations including a pure prefetch
strategy.
5.5.1
Adaptive read lookahead
Read lookahead causes the drive to continue reading data from the disc
following a normal read I/O until the read-ahead parameters are satisfied
(prefetch). If subsequent I/O requests can be satisfied from the prefetched
data in the data buffer, there is a significant improvement in performance
since a disc access is eliminated. If subsequent I/O requests cannot be
satisfied from the prefetched data, there is a reduction in performance due
to prefetch overhead.
The adaptive read lookahead feature suspends the prefetch operation if
three subsequent read I/O requests are not satisfied from the prefetched
data. This improves performance because unnecessary prefetches are
avoided. Prefetch is reinstated if an I/O request is sequential to a previous
I/O request.
5.6
Caching write data
Write caching is a drive-write operation, which uses a drive’s buffer storage
area where data to be written to the disc is stored while the drive performs
the Write command.
Write caching is enabled along with read caching. Default is cache enabled.
For write caching, the same buffer space and segmentation is used as set
up for read functions. When a write command is issued, the cache is first
checked to see if any logical blocks to be written are already stored in the
cache from a previous read or write command. If there are, the respective
cache segments are cleared. The new data is cached for subsequent read
commands.
Barracuda 1 and 2 Product Manual, Rev. C
17
If a 10-byte CDB write command (2Ah) is issued with the data page out (DPO)
bit set to 1, no write data is cached, but the cache segments are still checked
and cleared, if needed, for any logical blocks that are being written (see the
SCSI-2 Interface Product Manual ).
If the number of write data logical blocks exceeds the size of the segment
being written into when the end of the segment is reached, data is written into
the beginning of the same cache segment, overwriting data that was written
there at the beginning of the operation. However, the drive does not overwrite
data that has not yet been written to the disc.
5.7
Synchronized spindle operation
The synchronized spindle operation allows several drives operating from the
same host to operate their spindles at the same synchronized rotational rate.
Drives operating in a system in synchronized mode increase the system’s
capacity and transfer rate in a cost-effective manner.
The interface consists of a twisted-pair cable, which connects the drives in
the synchronized system in a daisy-chain configuration as shown in
Figure 4.
Sync Interface
Master Sync
Source
Host
(or other drive)
+5V
Drive 1
System
Interface
J4
1
Spindle
Control
2
RT
J4
1
Spindle
Control
2
+5V
Drive 2
RT
J4
1
Spindle
Control
+5V
Drive n
2
RT
Figure 4. Synchronized drive interconnect diagram
The host can reconfigure the drive any time after power-up to be the
master or a slave by using the Mode Select command on the Rigid Disc
Drive Geometry page. The master provides the reference signal to which
all other drives phase-lock, including the master. There is only one master
per system, and that can be a drive or the host computer. All drives may
be configured as slaves allowing the host to provide the reference signal.
Each drive also can be configured for the non-synchronized mode in which
it ignores any reference signal that might be present—this is the default
mode as shipped from the factory. Connect the synchronized reference
signal to the host only if the host provides the reference signal. If the host
does not provide the reference signal, do not connect the host.
18
Barracuda 1 and 2 Product Manual, Rev. C
Rotational position locking
Note. Mode Select page 4, byte 17, bits 1 and 0.
RPL
Description
00b
Spindle synchronization is disabled (default value)
01b
The target operates as a synchronized-spindle slave
10b
The target operates as a synchronized-spindle master
11b
The target operates as a synchronized-spindle master control
(not supported by the disc drive)
The VIC 2 LSI on the master drive provides the reference signal (SSREF+).
The index signal generates a 120 Hz signal. The signal is normally
false/negated (nominal 0V) and makes a transition to the true/asserted
(nominal +5V) level to indicate the reference position during the revolution
period. Master and slave drives use the trailing (falling) edge of the
reference signal to phase-lock their spindles. A maximum of 10 seconds
is allowed for a slave to synchronize with the reference signal. Figure 5
shows the characteristics of the reference signal.
Spindle synchronization input requirements:
SSREF +:Period (T) 0.0083 seconds (± 1.0% max)
Cycle-to-cycle variance: ± 10 microseconds
Phase error while synchronized: ± 20 microseconds
T
1
SSREF +
0
1.0 µsec min.
1.37 µsec max.
Figure 5. Synchronized reference signal characteristics
SCSI interface factors
The Rotational Position Locking (RPL) field in byte 17 (bits 0 and 1) of the
Rigid Disc Drive Geometry mode parameters page (page 04h) is used for
enabling and disabling spindle synchronization mode (see the SCSI-2
Interface Product Manual ). If the target fails to synchronize, it creates a unit
attention condition to all initiators. The sense key is set to Unit Attention and
the additional sense code is set to Spindle Synchronized (5C01).
After reaching synchronization, if the target detects a change of synchronization and:
1. If the logical unit is not executing an I/O process for the initiator, then the
target creates a unit attention condition. The sense key is set to Unit
Attention and the additional sense code is set to Spindle Synchronized
(5C01) or Spindle Not Synchronized (5C02).
2. If the logical unit is executing an I/O process and no other error occurs,
then the target returns Check Condition status. The sense key is set to
Recovered Error if the target is able to complete the I/O process or to
Hardware Error if the target is unable to complete the I/O process. The
additional sense code is set to Spindle Synchronized (5C01) or Spindle
Not Synchronized (5C02).
Barracuda 1 and 2 Product Manual, Rev. C
19
You may operate the drive with a rotational skew when synchronized. The
rotational skew is applied in the retarded direction (lagging the synchronizedspindle master control). A rotational offset of up to 255/256 of a revolution
lagging may be selected. Select the amount of offset by using the Mode
Select command, Rigid Disc Drive Geometry page (page 04h), byte 18 (see
the SCSI-2 Interface Product Manual ). The value in byte 18 (0–FFh) is the
numerator of a fractional multiplier that has 256 as the denominator. For
example, 40h selects 40h/FFh or 1/4 of a revolution lagging skew, 80h
selects 1/2 of a revolution lagging skew, etc. Since the drive supports all
offset values from 0 to 255, values sent by the initiator are not rounded off.
The drive’s translation of the digital offset values to physical rotational offsets
results in offset values whose phase error lies within the ± 20 microseconds
phase error with respect to the supplied 120 Hz reference signal.
The drive does not have the capability to adjust the rotational offset value
requested by the initiator to a physical offset in the drive that corresponds in
any way to sector boundaries or changes in ZBR zones. The initiator must
formulate these boundaries or changes, if required, to calculate the value of
offset it sends to the drive.
20
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
6.0
21
Reliability specifications
The following reliability specifications assume correct host and drive
interface, including all interface timings, power supply voltages, and
environmental requirements.
6.1
Seek error rate
Less than 10 errors in 108 seeks
Recoverable error rate
Less than 10 errors in 1011 bits transferred
(using default settings)
Unrecovered data
Less than 1 sector in 1014 bits transferred
Miscorrected data
Less than 1 sector in 1021 bits transferred
MTBF
500,000 hours
Service life
5 years
Preventive maintenance
None required
Error rates
The error rates stated in this manual assume the following:
• The drive is operated using DC power as defined in Section 7.2.
• The drive has been formatted with SCSI format commands.
• Errors caused by media defects or host system failures are excluded from
error rate computations. Refer to Section 9.0.
6.1.1
Environmental interference
When evaluating system operation under conditions of electromagnetic
interference (EMI), the performance of the drive within the system is
considered acceptable if the drive does not generate an unrecoverable
condition.
An unrecoverable error or condition is defined as one that:
• is not detected and corrected by the drive itself;
• is not capable of being detected from the error or fault status provided
through the drive or SCSI interface; or
• is not capable of being recovered by normal drive or system recovery
procedures without operator intervention.
6.1.2
Write errors
Write errors can occur as a result of media defects, environmental interference, or component malfunction. Therefore, write errors are not predictable
as a function of the number of bits passed.
If an unrecoverable write error occurs because of a component malfunction
in the drive, the error is classified as a failure affecting MTBF. Unrecoverable
write errors are those that cannot be corrected within two attempts at writing
the record with a read verify after each attempt (excluding media defects).
22
6.1.3
Barracuda 1 and 2 Product Manual, Rev. C
Seek errors
A seek error is defined as a failure of the drive to position the heads at the
addressed track. There must be no more than one recoverable seek error in
107 physical seek operations. After detecting an initial seek error, the drive
automatically reseeks to the addressed track up to three times. If a reseek
is successful, the extended sense report indicates a Seek-Positioning Error
(15h), No-Seek-Complete Error (02h), or Track-Follow Error (09h), and the
sense key reports a recovered error (1h). If all three reseeks fail, a SeekPositioning Error (15h) is reported with a Medium (3h) or Hardware Error (4h)
reported in the sense key. This is an unrecoverable seek error. Unrecoverable seek errors are classified as failures for MTBF calculations. Refer to
Section 5.1.1.2 of the SCSI-2 Interface Product Manual (part number
77738479).
6.2
Reliability and service
You can enhance the reliability of Barracuda 1 and 2 disc drives by ensuring
that the drive receives adequate cooling. This section provides recommended air-flow information, temperature measurements, and other information that may be used to enhance the service life of the drive.
6.2.1
Mean time between failures (MTBF)
The production disc drive achieves an MTBF of 500,000 hours when
operated in an average local disc drive ambient temperature of 95°F (35°C)
or less. Short-term excursions up to the specification limits (122°F, 50°C) of
the operating environment will not affect MTBF performance.
The following expression defines MTBF:
MTBF =
Estimated power-on operating hours in the period
Number of drive failures in the period
Estimated power-on operating hours means the estimated total power-on
hours for all drives in service.
Drive failure means any stoppage or substandard performance caused by
drive malfunction.
Data is calculated on a rolling-average base for a minimum period of six
months.
6.2.2
Air flow
The rack, cabinet, or drawer environment for the Barracuda 1 and 2 drive
must provide cooling of the electronics and head and disc assembly (HDA).
You should confirm that adequate cooling is provided using the temperature
measurement guidelines described below.
Orient the drive or direct air flow so that the least amount of air-flow
resistance is created while providing air flow to the electronics and HDA.
Also, choose the shortest possible path between the air inlet and exit to
minimize the travel length of air heated by the Barracuda 1 and 2 drive and
other heat sources within the rack, cabinet, or drawer environment.
Possible air-flow patterns are shown in Figure 6. Create the air-flow patterns
by using one or more fans, either forcing or drawing air as shown in the
illustrations. Other air-flow patterns are acceptable as long as the temperature measurement guidelines are met.
Barracuda 1 and 2 Product Manual, Rev. C
23
Above unit
Note. Air flows in the direction shown (back to front)
or in reverse direction (front to back)
Under unit
Above unit
Note. Air flows in the direction shown or
in reverse direction (side to side)
Figure 6. Air-flow pattern (ST11950N drive shown)
Under unit
24
Barracuda 1 and 2 Product Manual, Rev. C
To confirm that required cooling for the Barracuda electronics and HDA is
provided, place the drive in its final mechanical configuration, perform
random write/read operations, and after the temperatures stabilize, measure
the case temperature of the components listed below.
Air-flow cooling
ST11950N and ST12550N single-ended drives
Card
Component
Reference
TYFX
TYFX
TYFX
TYFX
TYFX
HDA housing
Transmitter
Writer
LSI
VIC2
1021
U5
U35
U4
U20
U55
Figure 11
MTBF
500k hours
case temperature (°C)
57
66
60
59
57
48
The air-flow pattern with which the temperature guidelines above were
generated is shown in Figure 6 (opposite direction). Local average air
velocity was 0.61 msec (120 lfpm) and inlet air temperature to the drive was
30°C (86°F).
The maximum allowable HDA case temperature is 60°C.
U5
U4
U35
U20
U55
Figure 7. TYFX temperature measurement locations
Barracuda 1 and 2 Product Manual, Rev. C
25
Air-flow cooling
ST11950ND and ST12550ND differential drives
Card
Component
Reference
UYFX
UYFX
UYFX
UYFX
UYFX
HDA housing
Transmitter
Writer
LSI
VIC2
1021
U5
U35
U4
U20
U55
Figure 11
MTBF
500k hours
case temperature (°C)
57
66
60
59
57
48
The air-flow pattern with which the temperature guidelines above were
generated is shown in Figure 6 (opposite direction). Local average air
velocity was 0.61 msec (120 lfpm) and inlet air temperature to the drive was
30°C (86°F).
The maximum allowable HDA case temperature is 60°C.
U5
U4
U35
U20
Figure 8. UYFX temperature measurement locations
U55
26
Barracuda 1 and 2 Product Manual, Rev. C
Air-flow cooling
ST11950W and ST12550W wide single-ended drives
Card
Component
Reference
TYGX
TYGX
TYGX
TYGX
TYGX
HDA housing
Transmitter
Writer
LSI
VIC2
1021
U5
U35
U4
U20
U55
Figure 11
MTBF
500k hours
case temperature (°C)
57
66
60
59
57
48
The air-flow pattern with which the temperature guidelines above were
generated is shown in Figure 6 (opposite direction). Local average air
velocity was 0.61 msec (120 lfpm) and inlet air temperature to the drive was
30°C (86°F).
The maximum allowable HDA case temperature is 60°C.
U5
U4
U35
U20
U55
Figure 9. TYGX temperature measurement locations
Barracuda 1 and 2 Product Manual, Rev. C
27
Air-flow cooling
ST11950WD and ST12550WD wide differential drives
Card
Component
Reference
PYGX
PYGX
PYGX
PYGX
PYGX
HDA housing
Transmitter
Writer
LSI
VIC2
1021
U5
U35
U4
U20
U55
Figure 11
MTBF
500k hours
case temperature (°C)
57
66
60
59
57
48
The air-flow pattern with which the temperature guidelines above were
generated is shown in Figure 6 (opposite direction). Local average air
velocity was 0.61 msec (120 lfpm) and inlet air temperature to the drive was
30°C (86°F).
The maximum allowable HDA case temperature is 60°C.
U5
U35
U4
U20
U55
Figure 10. PYGX temperature measurement locations
Measure the HDA housing temperature at the location specified in Figure 11.
1.0
0
.50
Figure 11. Temperature measurement location
28
6.2.3
Barracuda 1 and 2 Product Manual, Rev. C
Preventive maintenance
No preventive maintenance is required.
6.2.4
Service life
The drive has a useful service life of 5 years. Depot repair or replacement of
major parts is permitted during this period.
6.2.5
Service philosophy
Special equipment is required to repair the drive’s HDA. To achieve the
5-year service life, repairs must be performed only at a properly equipped
and staffed service and repair facility. Troubleshooting and repair of PCBs
in the field is not recommended because of the extensive diagnostic
equipment required for effective servicing. Also, there are no spare parts
available for this drive. The drive’s warranty is voided if the HDA is opened.
6.2.6
Installation
The drive is designed, manufactured, and tested with a “plug in and play”
installation philosophy. This philosophy minimizes the requirements for
highly trained personnel to integrate the drive into the OEM’s system,
whether in a factory or field environment. Refer to Section 4.4 and to the
Barracuda 1 and 2 Installation Guide (83327770) for installation instructions.
The drive has been low-level formatted at the factory and does not need to
be reformatted.
6.2.7
Service tools
No special tools are required for site installation or recommended for site
maintenance. Refer to Section 6.2.3. The depot repair philosophy of the drive
precludes the necessity for special tools. Field repair of the drive is not
practical because users cannot purchase individual parts for the drive.
6.2.8
Hot plugging Barracuda 1 and 2 disc drives
Caution. Hot-plug drives are not designed for simultaneous power disconnection and physical removal.
During power-up and power-down periods, the hot SCSI connect/disconnect
capability does not produce glitches or any corruptions on an active SCSI
bus. Barracuda 1 and 2 drives conform to the SCSI-3 standard requirements
for glitch-free power-on and power-off. The drive maintains the high-impedance state of the device connector contacts during a power cycle until the
transceiver is enabled.
Note. The systems integrator must ensure that no temperature, energy, or
voltage hazard is presented during the hot connect/disconnect operation.
Procedure:
1. Configure the drive with no connection between the drive and the
TRMPWR signal on the SCSI bus. To accomplish this, remove all
jumpers from connector J1.
2. Ensure that all SCSI devices on the bus have receivers that conform to
the SCSI-3 standard.
Barracuda 1 and 2 Product Manual, Rev. C
29
3. Eliminate all I/O processes for the drive.
4. Wait until the drive motor and discs have come to a complete stop prior
to changing the plane of operation, ensuring data integrity.
5. Insert or remove the drive after meeting the following conditions:
Caution. Do not hot-plug the first or last device on the SCSI bus (the
SCSI bus termination must be external to the drive you are
inserting or removing).
a. If you are inserting the drive, connect its power ground and logic
ground at least 1 millisecond before coming into contact with the bus
connector. Maintain these ground connections during and after connecting the device to the bus.
b. If you are removing the device, maintain its power ground and logic
ground connection for at least 1 millisecond after disconnecting the
device from the bus.
c. You may simultaneously switch the power to the electronics and
mechanics of the drive with the bus contacts, if the power distribution
system is able to maintain adequate power stability to other devices
during the transition and if you have met the grounding requirements
given in steps 5a and 5b.
Note. Do not remove or add terminator power or resistance to the SCSI bus
while hot plugging a disc drive.
30
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
7.0
31
Physical/electrical specifications
This section provides information relating to the physical and electrical
characteristics of Barracuda 1 and 2 drives.
7.1
AC power requirements
None.
7.2
DC power requirements
The voltage and current requirements for a single drive are shown in
Tables 1 and 2 (table notes follow Table 2). Values indicated apply at the
drive’s power connector.
Table 1. DC power requirements
for ST11950N/ND and ST12550N/ND drives
Max operating current DC 3σ [1]
ST11950N &
ST11950ND &
ST12550N
ST12550ND
5V[8] 12V
5V[8] 12V
[2]
±5% ±5%
±5%
±5%[2]
Amps
1.1
0.95
1.5
0.95
Avg idle current OD DC X
[1] [9]
1.0
0.84
1.1
0.84
Max start current
(peak) DC 3σ
(peak) AC 3σ
[3] [6]
[3]
1.0
–
2.18
3.1
1.1
–
2.18
3.1
Delay motor start (max)
DC 3σ
[1] [4]
1.06
0.19
1.1
0.2
[1] [7]
[1]
1.07
1.1
1.15
0.91
0.95
1.87
1.47
1.5
1.8
0.91
0.95
1.86
OD DC X
[1]
1.0
0.84
1.1
0.84
ID DC X
[1]
1.0
0.9
1.1
0.9
[1] [11]
1.1
1.2
0.85
1.2
1.6
1.8
0.85
1.2
[1] [10]
[1]
1.0
1.1
1.2
1.2
1.2
1.8
1.1
1.2
1.7
1.2
1.2
1.8
Voltage regulation[5]
Notes
Peak operating current
Typical DC X
Maximum DC 3σ
Maximum (peak) AC 3σ
Track following at
Read track
OD DC 3σ
AC 3σ
Seeking
Typical DC X
Maximum DC 3σ
Maximum (peak) AC 3σ
32
Barracuda 1 and 2 Product Manual, Rev. C
Table 2. DC power requirements
for ST11950W/WD and ST12550W/WD drives
Voltage regulation[5]
Notes
Max operating current DC 3σ [1]
ST11950W &
ST11950WD &
ST12550W
ST12550WD
5V[8] 12V
5V[8] 12V
±5% ±5%[2]
±5%
±5%[2]
Amps
1.04 0.95
1.3
0.95
Avg idle current
OD DC X
[1] [9]
1.0
0.84
1.1
0.84
Max start current
(peak) DC 3σ
(peak) AC 3σ
[3] [6]
[3]
1.0
–
2.18
3.1
1.1
–
2.18
3.1
Delay motor start (max)
DC 3σ
[1] [4]
1.0
0.19
1.1
0.19
[1] [7]
[1]
1.03
1.04
1.2
0.91
0.95
1.87
1.21
1.3
2.0
0.91
0.95
1.87
OD DC X
[1]
1.0
0.84
1.1
0.84
ID DC X
[1]
1.0
0.9
1.1
0.9
[1] [12]
1.1
1.3
0.85
1.2
1.4
2.0
0.85
1.2
[1] [10]
[1]
1.0
1.1
1.2
1.2
1.2
1.8
1.1
1.2
2.0
1.2
1.2
1.8
Peak operating current
Typical DC X
Maximum DC 3σ
Maximum (peak) AC 3σ
Track following at
Read track
OD DC 3σ
AC 3σ
Seeking
Typical DC X
Maximum DC 3σ
Maximum (peak) AC 3σ
Notes:
[1] Measured with average reading DC ammeter. Instantaneous +12V
current peaks will exceed these values.
[2] A –10% tolerance is permissible during initial start of the spindle and
must return to ±5% before reaching 7,200 RPM. The ±5% must be
maintained after the drive signals that its power-up sequence has
been completed and that it can accept selection by the host initiator.
[3] See Figure 12.
[4] This condition occurs when the Motor Start Option is enabled and the
drive has not yet received a start motor command.
[5] See Section 7.2.1. Specified voltage tolerance includes ripple, noise,
and transient response.
[6] At power-up, the motor current regulator limits the 12V current to an
average value of less than 2.0A, although instantaneous peaks may
exceed this value. These peaks should measure 5 msec duration or less.
Barracuda 1 and 2 Product Manual, Rev. C
33
[7] Operating condition is defined as a third-stroke seek at OD and read one
track. A command is issued every 0.07 sec.
[8] No terminator power. See Section 11.7.3.4.
[9] Idle is defined as track following at OD.
[10] Seeking is defined as a third-stroke seek at OD. A command is issued
every 20 msec.
[11] Read track is defined as repeat reads of track 15 with a 91% duty cycle.
[12] Read track is defined as repeat reads of track 15 with a 75% duty cycle.
Notes:
1. Minimum current loading for each supply voltage is not less than 7%
of the maximum operating current shown.
2. The +5V and +12V supplies use separate ground returns.
3. Where power is provided to multiple drives from a common supply,
careful consideration for individual drive power requirements should
be noted. Where multiple units are powered on simultaneously, the
peak starting current must be available to each device.
7.2.1
Conducted noise immunity
Noise is specified as a periodic and random distribution of frequencies
covering a band from DC to 10 MHz. Maximum allowed noise values given
below are peak-to-peak measurements and apply at the drive’s power
connector.
1 to 100 kHZ
7.2.2
100 kHz to 10 MHz
+5V
150 mV
100 mV
+12V
150 mV
100 mV
Power sequencing
The drive does not require power sequencing. The drive protects against
inadvertent writing during power-up and down. Daisy-chain operation requires that power be maintained on the terminated device to ensure proper
termination of the peripheral I/O cables.
To automatically delay motor start based on the target ID (SCSI ID), select
the Delay Motor Start option and deselect the Enable Motor Start option. See
Section 10.1 for pin selection information.
To delay the motor until the drive receives a Start Unit command, select the
Enable Motor Start option.
34
Barracuda 1 and 2 Product Manual, Rev. C
7.2.3
12V current profile
Figure 12 identifies the drive’s +12V current profile. The current during the
various times is as shown.
3.0
2.85
2.5
Peak AC
+12V CURRENT (A)
Nominal (average) curve
2.0
1.9
1.5
Minimum AC
1.0
0.5
T2
T0
T5
T3
0.0
T1
0
5
10
T6
T4
15
20
T7
25
30
TIME (S)
Figure 12. Barracuda 1 and 2 drives typical + 12V current profiles
T0
Power is applied to the drive.
T1
Controller self-tests are performed.
T2
The spindle begins to accelerate under current limiting after performing
internal diagnostics. See Note 1 of Table 1.
T3
The spindle is up to speed and the head-arm restraint is unlocked.
T4
Heads move from the landing zone to the data area.
T5
The adaptive calibration sequence is performed.
T6
Thermal calibration.
T7
Calibration is complete and the drive is ready for reading and writing.
Note. All times and currents are typical. See Tables 1 and 2 for maximum
current requirements.
Barracuda 1 and 2 Product Manual, Rev. C
7.3
35
Heat/power dissipation
The heat and power dissipation values for the Barracuda 1 and 2 drives are
listed below.
Typical seek and read
power dissipation*
ST11950N/W
ST12550N/W
16W
(55 BTUs/hr)
ST11950ND
ST12550ND
18W
(62 BTUs/hr)
ST11950WD
ST12550WD
17W
(58 BTUs/hr)
Typical power dissipation
under idle conditions
15W
(51 BTUs/hr)
15W
(51 BTUs/hr)
15W
(51 BTUs/hr)
*DC power average at nominal voltages
7.4
Environmental limits
Temperature and humidity must not cause condensation within the drive.
Altitude and atmospheric pressure specifications are referenced to a standard day at 58.7°F (14.8°C). Maximum wet bulb temperature is 82°F (28°C).
7.4.1
Temperature
a. Operating
The MTBF specification for the drive is based on operating at a local
ambient temperature of 95°F (35°C). Occasional excursions to drive
ambient temperatures of 122°F (50°C) may occur without impact to
specified MTBF. The enclosure for the drive should be designed such that
the temperatures at the locations specified in Section 6.2.2 are not
exceeded. Air flow may be needed to achieve these temperatures.
Continual or sustained operation at case temperatures above these
values may degrade MTBF.
The drive meets all specifications within a 41° to 122°F (5° to 50°C)
drive ambient temperature range with a maximum gradient of
36°F (20°C) per hour.
b. Non-operating
Non-operating temperature should remain between –40° to 158°F (–40°
to 70°C) package ambient with a maximum gradient of 36°F (20°C)
per hour. This assumes that the drive is packaged in the shipping
container designed by Seagate.
7.4.2
Relative humidity
The values below assume that no condensation on the drive occurs.
a. Operating
5% to 95% relative humidity with a maximum gradient of 10% per hour
b. Non-operating
5% to 95% relative humidity
36
7.4.3
Barracuda 1 and 2 Product Manual, Rev. C
Effective altitude (sea level)
a. Operating
–1,000 to +10,000 feet (–305 to +3,048 meters)
b. Non-operating
–1,000 to +40,000 feet (–305 to +12,210 meters)
7.4.4
Shock and vibration
Shock and vibration limits are measured directly on the drive’s chassis.
Ensure that you use an enclosure that buffers and restricts the drive’s
movements to meet the shock and vibration requirements listed below.
The limits of shock and vibration defined within this manual are specified
with the drive mounted in one of the two methods shown in Figure 15.
7.4.4.1
Shock
a. Operating in a normal environment
The drive as installed for normal operation operates error free while
subjected to intermittent shock not exceeding:
2.0 Gs at a maximum duration of 11 msec (half-sinewave)
Shock may be applied in the X, Y, or Z axis.
b. Operating in an abnormal environment
The drive as installed for normal operation does not incur physical
damage while subjected to intermittent shock not exceeding:
10 Gs at a maximum duration of 11 msec (half-sinewave)
Shock occurring at abnormal levels may degrade operating performance
during the abnormal shock period. Specified operating performance
continues when normal operating shock levels resume.
Shock may be applied in the X, Y, or Z axis. Shock must not be repeated
more than two times per second.
c. Non-operating
The limits of non-operating shock apply to all conditions of handling and
transportation. This includes both isolated drives and integrated drives.
The drive does not cause drive damage or performance degradation
while subjected to non-repetitive shock not exceeding:
50 Gs at a maximum duration of 11 msec (half-sinewave)
Shock may be applied in the X, Y, or Z axis.
d. Packaged
The drive as packaged by Seagate for general freight shipment withstands a drop test against a concrete floor or equivalent with specifications not exceeding:
20 pounds (8.95 kg) for pack’s gross weight
42 inches (1,070 mm) for distance dropped
The drop test applies to a single- or multiple-drive pack.
Barracuda 1 and 2 Product Manual, Rev. C
7.4.4.2
37
Vibration
a. Operating in a normal environment
The drive as installed for normal operation operates error free while
subjected to continuous vibration not exceeding:
5-400 Hz @ 0.5 G in the X and Y axis
Vibration may be applied in the X, Y, or Z axis.
b. Operating in an abnormal environment
Equipment as installed for normal operation does not incur physical
damage while subjected to periodic vibration not exceeding:
15 minutes of duration at major resonant frequency
5-400 Hz @ 0.75 G
Vibration occurring at these levels may degrade operating performance
during the abnormal vibration period. Specified operating performance
continues when normal operating vibration levels are resumed—this
assumes system recovery routines are available.
Abnormal vibration may be applied in the X, Y or Z axis.
c. Non-operating
The limits of non-operating vibration apply to all conditions of handling
and transportation. This includes both isolated drives and integrated
drives.
The drive does not incur physical damage or degraded performance as
a result of continuous vibration not exceeding:
5-22 Hz @ 0.040 inches (1.02 mm) displacement
22-400 Hz @ 2.00 Gs
Vibration may be applied in the X, Y, or Z axis.
7.4.5
Air cleanliness
The drive is designed to operate in a typical office environment with minimal
environmental control.
7.4.6
Acoustics
Sound power during idle mode (when the drive is not seeking, reading, or
writing) is 4.7 bels typical when measured to ISO 7779 specifications.
7.5
Electromagnetic compatibility
As a component assembly, the drive is not required to meet any susceptibility performance requirements. The system integrator is responsible for
performing tests to ensure that equipment operating in the same system as
the drive does not adversely affect the performance of the drive. See
Section 7.2 “DC power requirements.”
38
7.6
Barracuda 1 and 2 Product Manual, Rev. C
Mechanical specifications
The following nominal dimensions do not include the decorative front-panel
accessory. Refer to the appropriate figure listed below for your drive’s
mounting configuration dimensions.
Height
Width
Depth
Weight
1.63 in
4.00 in
5.97 in
2.3 lb
41.4 mm
101.6 mm
151.6 mm
1.04 Kg
ST11950N/ND and ST12550N/ND drives
ST11950W/WD and ST12550W/WD drives
Figure 13
Figure 14
T
U
[1]
C
[3]
R
F
N
D
E
P
K
L
A
M
Notes:
[1] Mounting holes two on each
side, 6-32 UNC. Max screw
length into side of drive is
0.15 in. (3.81 mm).
[2] Mounting holes four on
bottom, 6-32 UNC. Max
screw length into bottom of
drive is 0.15 in. (3.81 mm).
B
[3] Power and interface
connections.
[4] Decorative front panel.
[2]
Inches
G
J
[4]
H
S
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
S
T
U
5.740
4.000
1.620
.615
4.000
.250
1.750
3.750
2.370
5.420
5.565
5.965
.195
.360
1.725
4.100
.190
0.015
± 0.010
± 0.010
± 0.034
± 0.020
± 0.005
± 0.005
± 0.010
± 0.010
± 0.010
± 0.020
± 0.010
± 0.020
± 0.015
± 0.015
± 0.010
± 0.010
± 0.010
max
Millimeters
145.80 ± .25
101.60 ± .25
41.14 ± .86
15.68 ± .50
101.60 ± .13
6.35 ± .13
44.45 ± .25
95.25 ± .25
60.20 ± .25
137.69 ± .50
141.35 ± .25
151.41 ± .50
4.95 ± .38
9.14 ± .38
43.82 ± .25
104.14 ± .25
4.83 ± .25
0.381 max
Figure 13. Mounting configuration dimensions for N/ND drives
Barracuda 1 and 2 Product Manual, Rev. C
39
T
U
[1]
C
[3]
R
F
N
D
E
P
K
L
A
M
Notes:
[1] Mounting holes two on each
side, 6-32 UNC. Max screw
length into side of drive is
0.15 in. (3.81 mm).
V
B
[2] Mounting holes four on
bottom, 6-32 UNC. Max
screw length into bottom of
drive is 0.15 in. (3.81 mm).
[3] Power and interface
connections.
[4] Decorative front panel.
[2]
Inches
G
J
[4]
H
S
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
S
T
U
V
5.740
4.000
1.620
.615
4.000
.250
1.750
3.750
2.370
5.420
5.565
5.968
.190
.347
1.725
4.100
.190
0.015
0.265
± 0.010
± 0.010
± 0.028
± 0.020
± 0.005
± 0.005
± 0.010
± 0.010
± 0.010
± 0.020
± 0.010
± 0.035
± 0.015
± 0.015
± 0.010
± 0.010
± 0.010
max
± 0.020
Millimeters
145.80 ± .25
101.60 ± .25
41.14 ± .68
15.68 ± .50
101.60 ± .13
6.35 ± .13
44.45 ± .25
95.25 ± .25
60.20 ± .25
137.69 ± .50
141.35 ± .25
151.58 ± .90
4.826 ± .38
8.81 ± .38
43.82 ± .25
104.14 ± .25
4.83 ± .25
0.381 max
6.73 ± .50
Figure 14. Mounting configuration dimensions for W/WD drives
40
7.6.1
Barracuda 1 and 2 Product Manual, Rev. C
Drive orientation
The balanced rotary arm actuator design of the drive allows it to be mounted
in any orientation. All drive performance evaluations have been done with the
drive in horizontal (discs level) and vertical (drive on its side) orientations,
which are the two preferred mounting orientations.
Figure 15. Recommended mounting (ST11950N shown)
7.6.2
Cooling
Ensure that the enclosure you use provides adequate cooling so that the
ambient temperature immediately surrounding the drive does not exceed
temperature conditions specified in Section 7.4.1. Ensure that you provide
adequate air circulation around the printed circuit boards (PCBs) to meet
the requirements of Section 6.2.2.
Barracuda 1 and 2 Product Manual, Rev. C
8.0
41
Media characteristics
This section provides information regarding the media used in Barracuda 1
and 2 disc drives.
8.1
Media description
The media used on the drive has a diameter of approximately 95 mm (3.7
inches). The aluminum substrate is coated with a thin-film magnetic material,
which has a proprietary protective layer for improved durability and environmental protection.
42
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
9.0
43
Defect and error management
The drive, as delivered, complies with this product manual. The read error
rates and specified storage capacities are not dependent on using defectmanagement routines by the host (initiator).
Defect and error management in the SCSI system involves the drive’s
internal defect/error management and SCSI system error considerations
(errors in communications between the initiator and the drive). Tools for
designing a defect/error management plan are briefly outlined in this section.
References to other sections are provided when necessary.
9.1
Defects and errors
Identified defects are recorded on the drive’s defects list (referred to as the
primary or ETF defect list). These known defects are reallocated during the
initial drive format at the factory. (See Format Unit command Section 5.2.1.2
in the SCSI-2 Interface Product Manual, part number 77738479.) Data
correction by ECC recovers data from additional flaws if they occur.
Details of the SCSI commands supported by the drive are described in the
SCSI-2 Interface Product Manual. Also, more information about the drive’s
Error Recovery philosophy is presented in Section 6 of the SCSI-2 Interface
Product Manual.
44
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
10.0
45
Option/configuration headers
This section describes how to configure Barracuda 1 and 2 drives using the
option headers on the drives. These option headers may be used to
customize many functions of the drives for your particular system.
10.1
Drive ID/option select headers
The headers described in this section enable you to configure the drive to
meet specific functionality requirements.
10.1.1
ST11950N/ND and ST12550N/ND configuration
I/O Terminator Packs
(single-ended I/O only)
SCSI I/O
Connector
Pin 1 End
(of terminator)
Pin 1
J4
J01
DC Power Connector
Figure 16. ST11950N/ND and ST12550N/ND physical interface
46
Barracuda 1 and 2 Product Manual, Rev. C
Figure 17 illustrates ST11950N/ND and ST12550N/ND SCSI ID and option
select jumper connectors.
Pin 1
J4
11 10 9
8
7
6
5
4
3
2
SCSI
Connector
1
SCSI ID = 0
SCSI ID = 1
SCSI ID = 2
SCSI ID = 3
SCSI ID = 4
SCSI ID = 5
SCSI ID = 6
SCSI ID = 7
Reserved
Parity Disable
Enable Motor Start
Delay Motor Start
Write Protect
Remote LED Connector
J01
J4
Reserved
SSREF
Spindle Sync Cable Connector
Pin 3
J01
*
*
Term. Power from Drive
Term. Power from SCSI Bus
Term. Power to SCSI Bus
*
Term. Power to SCSI Bus and Drive
B Position
A Position
Power
Connector
Pin 1
Pin 2
Position 1
Position 2
Position 1
Position 2
Position 1
Position 2
Position 1
Position 2
* Valid for single-ended (“N”) drives only.
Figure 17. ST11950N/ND and ST12550N/ND jumper connectors
Pin 1
Pin 1
Barracuda 1 and 2 Product Manual, Rev. C
ST11950N and ST12550N
47
Block Pins
Function
J01
1&2
Terminator power from the drive
1&3
Terminator power to the SCSI bus
2&4
Terminator power from the SCSI bus
1 & 3 and Terminator power to the SCSI bus and drive
2&4
ST11950ND and ST12550ND
J01
1&3
Terminator power to the SCSI bus
ST11950N/ND and
ST12550N/ND
J4
1&2
Spindle sync cable connector
Pin 1 is SSREF+
Pin 2 is ground
3&4
Reserved
5&6
Remote LED connector
Pin 5 is cathode (negative)
Pin 6 is anode (positive)
7&8
Write Protect option. Jumper installed write protects the entire disc drive. Default is no jumper.
9 & 10
Delay Motor Start option. Jumper installed causes
the drive to wait ten (10) seconds for each target
ID number before starting the spindle automatically. Default is no jumper.
Example:
Target ID is equal to three (3)
3 X 10 = 30
Target spindle motor starts after
thirty (30) seconds
11 & 12
Enable Motor Start option. Jumper installed
causes the target to wait for the Start Unit command from the SCSI host. No jumper installed
causes the unit to start according to the Delay
Motor Start option (J4 pins 9 and 10). Default is
no jumper.
13 & 14
Parity Disable option. Jumper installed causes
parity checking and error reporting to be disabled. Default is no jumper.
15 & 16
Reserved
17 & 18*
SCSI ID bit 0
19 & 20*
SCSI ID bit 1
21 & 22*
SCSI ID bit 2
*See Figure 17 to set the SCSI ID.
48
ST11950W/WD and ST12550W/WD configuration
SCSI I/O
Connector
Pin 1
J01
J4
J5
DC Power
Connector
Figure 18. ST11950W/WD and ST12550W/WD physical interface
Figure 19 illustrates ST11950W/WD and ST12550W/WD SCSI ID and option
select jumper connectors.
Position
SCSI
Connector
Pin 1
J5
6
5
4
3
2
1
SCSI ID = 0
SCSI ID = 1
SCSI ID = 2
SCSI ID = 3
SCSI ID = 4
SCSI ID = 5
SCSI ID = 6
SCSI ID = 7
Pin 1
SCSI ID = 8
J5
SCSI ID = 9
SCSI ID = 10
Pin 1
SCSI ID = 11
SCSI ID = 12
SCSI ID = 13
SCSI ID = 14
Pin 1
Remote LED Connector
Spindle Sync
Cable Connector
Positive
(anode)
SSREF
Enable Drive Terminators*
Reserved
Parity Disable
Power
Connector
J4
Pin 1
J4
Position
Pin 1
Negative
(cathode)
7
6
5
4
3
2
1
J01
Pin 3
J01
* Term. Power from Drive
* Term. Power from SCSI Bus
Term. Power to SCSI Bus
* Term. Power to SCSI Bus and Drive
Enable Motor Start
Delay Motor Start
* Valid for single ended drives only.
Write Protect
Figure 19. ST11950W/WD and ST12550W/WD jumper connectors
B Position
SCSI ID = 15
Pin 1
A Position
10.1.2
Barracuda 1 and 2 Product Manual, Rev. C
Pin 1
Pin 2
Position 1
Position 2
Position 1
Position 2
Position 1
Position 2
Position 1
Position 2
Barracuda 1 and 2 Product Manual, Rev. C
ST11950W and ST12550W
49
Block Pins
Function
J01
1&2
Terminator power from the drive
1&3
Terminator power to the SCSI bus
2&4
Terminator power from the SCSI bus
1 & 3 and Terminator power to the SCSI bus and drive
2&4
ST11950WD and ST12550WD J01
1&3
Terminator power to the SCSI bus
ST11950W/WD and
ST12550W/WD
1&2
Write Protect option. Jumper installed write protects the entire disc drive. Default is no jumper.
3&4
Delay Motor Start option. Jumper installed causes
the drive to wait ten (10) seconds for each target
ID number before starting the spindle automatically. Default is no jumper.
J4
Example:
Target ID is equal to three (3)
3 X 10 = 30
Target spindle motor starts after
thirty (30) seconds
J5
5&6
Enable Motor Start option. Jumper installed
causes the target to wait for the Start Unit command from the SCSI host. No jumper installed
causes the unit to start according to the Delay
Motor Start option (J4 pins 3 and 4). Default is no
jumper.
7&8
Parity Disable option. Jumper installed causes
parity checking and error reporting to be disabled. Default is no jumper.
9 & 10
Reserved
11 & 12
Enable Drive Terminator. Jumper installed enables the Drive Terminator. Default is no jumper.
13 & 14
Reserved
1 & 2*
SCSI ID bit 0
3 & 4*
SCSI ID bit 1
5 & 6*
SCSI ID bit 2
7 & 8*
SCSI ID bit 3
9 & 10
Remote LED connector
Pin 9 is cathode (negative)
Pin 10 is anode (positive) and is current
limited through a 1K ohm, 1/10W resistor
11 & 12
Spindle sync cable connector
Pin 11 is SSREF+
Pin 12 is ground
*See Figure 19 to set the SCSI ID.
50
10.2
Barracuda 1 and 2 Product Manual, Rev. C
Synchronized spindles interface
The synchronized spindles interface (SSI) allows several drives operating
from the same host to operate their spindles at a synchronized rotational rate.
Details of the electrical and physical interfaces follow in Section 10.2.1. The
system operation is described in Section 5.7.
10.2.1
Electrical description
The electrical interface consists of one digital TTL reference index signal and
ground. The reference index signal (SSREF+) is an output if the drive is
configured as a master and is an input otherwise. The reference index signal
is connected from drive to drive in a daisy-chain fashion as shown in Figure 4.
10.2.1.1
Drivers and receivers
Figure 20 shows a diagram of the driver/receiver circuit. The driver circuits
have the following electrical specifications:
Negated (false): 0.0V to +0.4V @ I = –24 mA (max)
Asserted (true): +2.24V to +5.25V @ I = +250 µA
Main PWA
Open
Collector
Driver
2.21K Ohm
Receiver
SSREF +
+5V
GND
J4 - 1 (N/ND Drives)
J5 - 11 (W/WD Drives)
J4 - 2 (N/ND Drives)
J5 - 12 (W/WD Drives)
Figure 20. SCSI reference index signal driver/receiver combination
Barracuda 1 and 2 Product Manual, Rev. C
10.2.1.2
51
Termination
The reference index signal (SSREF+) is terminated with a 2.21K ohm
resistor. Each single-ended drive has a terminator resistor located on the
main PCB. The terminator resistor is not removable and is always in the
circuit. A diode prevents current backfeed.
10.2.1.3
Physical interface
ST11950N/ND and ST12550N/ND drives
Dimensions of the ST11950N/ND and ST12550N/ND J4 connector mounted
on the main PCB to interconnect the drives are shown in Figure 21. It is a 22pin, 11-position gold header type connector. Only pins 1 and 2 are used for
connecting the reference index signal cable, as shown in Figure 17. Pin 1 is
SSREF+ and pin 2 is ground.
.866
(22 mm)
.079 (2 mm)
J04
.079
(2 mm)
.787
(20 mm)
Figure 21. ST11950N/ND and ST12550N/ND configuration
select header specification
ST11950W/WD and ST12550W/WD drives
Dimensions of the ST11950W/WD and ST12550W/WD J5 connector
mounted on the main PCB to interconnect the drives are shown in
Figure 22. It is a 12-pin, 6-position gold header type connector. Only pins
11 and 12 are used for connecting the reference index signal cable, as
shown in Figure 19. Pin 11 is SSREF+ and pin 12 is ground.
.079
(2 mm)
.520
(13.2 mm)
Pin 1
.185
(4.7 mm)
J5
.079
(2 mm)
Figure 22. ST11950W/WD and ST12550W/WD configuration
select header specification
52
10.3
Barracuda 1 and 2 Product Manual, Rev. C
Grounding
Signal ground (PCB) and HDA ground are connected together in the
Barracuda 1 and 2 family drives—do not separate this connection. Maximizing the conductive contact area between HDA ground and system ground
may reduce radiated emissions. If you do not want to connect HDA ground
to the system chassis, you must provide a nonconductive (electrically
isolating) method of mounting the drive in the host equipment. This may
increase radiated emissions and is the system integrator’s responsibility.
Barracuda 1 and 2 Product Manual, Rev. C
11.0
53
Interface requirements
This section describes the Barracuda 1 and 2 interface requirements.
11.1
General description
This section contains drive-specific interface information. The major portion
of the interface requirements/implementation is described in the SCSI-2
Interface Product Manual (part number 77738479).
11.2
SCSI interface messages supported
Table 3 lists the messages supported by the Barracuda SCSI-1 and
SCSI-2 modes.
Table 3. SCSI messages supported
Message name
Abort
Abort tag
Msg
code
06h
0Dh
Supported by
SCSI-1
SCSI-2
Y
Y
Y
Y
Bus device reset
0Ch
Y
Y
Clear queue
Command complete
Continue I/O Process
0Eh
00h
12h
N
Y
N
Y
Y
N
Disconnect
04h
Y
Y
Extended messages
01h***
Y
Y
Identify
Ignore wide residue (two bytes)
Initiate recovery
Initiator detected error
80h-FFh
23h
0Fh
05h
Y
N
N
Y
Y
N
N
Y
Linked command complete
Linked command complete with flag
0Ah
0Bh
Y
Y
Y
Y
Message parity error
Message reject
Modify data pointer
09h
07h
***
Y
Y
N
Y
Y
N
No operation
08h
Y
Y
Queue tag messages (two bytes)
Head of queue tag
Ordered queue tag
Simple queue tag
21h
22h
20h
N
N
N
Y
Y
Y
Release recovery
Restore pointers
10h
03h
N
Y
N
Y
Save data pointer
Synchronous data transfer request
02h
***
Y
Y
Y
Y
Target transfer disable
Terminate I/O process
13h
11h
N
N
N
N
Wide data transfer request
***
N
Y
*** Extended messages (see the SCSI-2 Interface Product Manual)
54
11.3
Barracuda 1 and 2 Product Manual, Rev. C
SCSI interface commands supported
Table 4 lists the SCSI interface commands supported in SCSI-1 and SCSI-2
modes. Barracuda 1 and 2 family drives can be changed back and forth
between SCSI-1 and SCSI-2 modes, using the Change Definition command.
Standard OEM drives are shipped set to operate in SCSI-2 mode.
Table 4. Supported commands
Command name
Change Definition
Compare
Copy
Copy and Verify
Command
code
40h
39h
18h
3Ah
Supported by
SCSI-1 SCSI-2
Y
Y
N
N
N
N
N
N
Format Unit [1]
04h
Y
Y
Inquiry
Date Code Page
Firmware Numbers Page
Implemented Operating Def. Page
Jumper Settings Page
Unit Serial Number Page
Vital Product Data Page
12h
Y
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Lock-Unlock Cache
Log Select
Log Sense
36h
4Ch
4Dh
N
N
N
Y
N
N
Mode Select
15h
Same pages as Mode Sense command
Mode Select (10)
55h
Mode Sense
1Ah
Caching Parameters Page (08h)
Control Mode Page (0Ah)
Disconnect/Reconnect Control Page (02h)
Error Recovery Page (01h)
Format Page (03h)
Notch and Partition Page (0C) (media zones)
Rigid Disc Drive Geometry Page (04h)
Unit Attention Page (00h)
Verify Error Recovery Page (07h)
Mode Sense (10)
5Ah
Y
Y
N
Y
N
N
Y
Y
Y
N
Y
Y
N
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Not used
Not used
Not used
Not used
Not used
Not used
Not used
42–4Bh
4E–54h
56–59h
5B–5Fh
60–BFh
C0–DFh
E0–FFh
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Prefetch
34h
N
N
continued
Barracuda 1 and 2 Product Manual, Rev. C
55
continued from previous page
Command name
Read
Read Buffer
Read Capacity
Read Defect Data
Read Extended
Read Long
Reassign Blocks
Receive Diagnostic Results
Supported Diagnostics Pages
Translate Page
Release
Request Sense
Actual Retry Count Bytes
Extended Sense
Field Pointer Bytes
Reserve
Extent Reservation
Third Party Reserve
Rezero Unit
Command
code
08h
3Ch
25h
37h
28h
3Eh
07h
1Ch
17h
03h
16h
01h
Search Data Equal
Search Data High
Search Data Low
Seek
Seek Extended
Send Diagnostics Page
Supported Diagnostics Pages
Translate Page
Set Limits
Start Unit/Stop Unit
Synchronize Cache
31h
30h
32h
0Bh
2Bh
1Dh
Supported by
SCSI-1 SCSI-2
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
N
N
Y
Y
Y
Y
Y
Y
N
N
Y
Y
Y
Y
33h
1Bh
35h
N
N
N
Y
Y
Y
Y
Y
N
Y
N
N
N
N
Y
Y
Y
Y
Y
N
Y
N
Test Unit Ready
00h
Y
Y
Verify
2Fh
Y
Y
Write
Write and Verify
Write Buffer
Write Extended
Write Long
Write Same
0Ah
2Eh
3Bh
2Ah
3Fh
41h
Y
Y
Y
Y
Y
N
Y
Y
Y
Y
Y
Y
[1] Format to any even number of bytes per sector from 180 to 4,096.
56
Barracuda 1 and 2 Product Manual, Rev. C
11.3.1
Inquiry data
Table 5 lists the Inquiry command data that the drive should return to the
initiator per the format provided in the SCSI-2 Interface Product Manual.
Table 5. Barracuda 1 and 2 family drive inquiry data
Bytes Data (hex)
0-15
16-31
32-47
48-63
64-79
80-95
96-111
112-127
128-143
144-147
00
[53
R#
00
00
00
00
39*
72
D#
00
54
R#
00
00
00
43
39*
69
D#
**
31
R#
00
00
00
6F
34*
67
D#
***
31
R#
00
00
00
70
20
68
D#
8F
39
S#
00
00
00
79
53
74
00
35
S#
00
00
00
72
65
73
00
30
S#
00
00
00
69
61
20
(1A)
20
S#
00
00
00
67
67
72
53
20
S#
00
00
00
68
61
65
45
20
S#
00
00
00
74
74
73
41
20
S#
00
00
00
20
65
65
47
20
S#
00
00
00
28
20
72
*
Copyright year (changes with actual year)
**
01 = SCSI-1 implemented
02 = SCSI-2 implemented (default)
The drive can be changed between these two configurations.
41
20
00
00
00
00
63
41
76
54
20
00
00
00
00
29
6C
65
45
20
00
00
00
00
20
6C
64
20 Vendor ID
20] Product ID
00
00
00
00
31* *Copyright
20
notice
20
*** 01 = Response data is in SCSI-1 format and has compatibility with Common Command Set data
02 = Response data is in SCSI-2 format (default)
The drive can be changed between these two configurations.
R# Four ASCII digits representing the last four digits of the product firmware release number
S# Eight ASCII digits representing the eight digits of the product serial number
D# Reserved 0000
()
[]
Byte 7 is 1A for N/ND drives and 3A for W/WD drives.
Bytes 16 through 31 identify the product ID including the model number (ST11950N/ND drive
shown).
ST11950W/WD codes: 53 54 31 31 39 35 30 20 20 20 20 20 20 20 20 20
ST12550N/ND codes: 53 54 31 32 35 35 30 20 20 20 20 20 20 20 20 20
ST12550W/WD codes: 53 54 31 32 35 35 30 20 20 20 20 20 20 20 20 20
Note. Code 20 indicates an empty-character position.
11.3.2
Mode sense data
Tables 6, 7, 8, and 9 list the data-byte values the drive returns in response
to the Mode Sense command pages for SCSI-1 and SCSI-2 implementation
(see the SCSI-2 Interface Product Manual).
Definitions:
DEF = Default value. Standard drives are shipped configured this way.
CHG = Changeable bits; indicates if the default value is changeable.
Barracuda 1 and 2 Product Manual, Rev. C
57
Table 6. Mode sense data, ST11950 default values
(SCSI-1 implementation)
Bytes 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Mode
Sense 64 00 10 08
Data 00 32 5F 77 00 00 02 00
<—————————Mode page headers and parameter data bytes—————————>
Mode
Page
DEF
01 81 06 04 1B 30 00 00 FF
CHG
01 81 06 EF FF 00 00 00 00
DEF
02 82 0A 80 80 00 0A 00 00 00 00 00 00
CHG
02 82 0A FF FF 00 00 00 00 00 00 00 00
DEF
03 83 16 00 0F 00 06 00 00 00 0F 00 51 02 00 00 01 00 07 00 10 40 00 00 00
CHG
03 83 16 FF FF FF FF 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00
DEF
04 84 12 00 0A 93 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00
CHG
04 84 12 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 FF 00
DEF
08 88 12 14 00 FF FF 00 00 00 9F 02 7C 80 03 00 00 00 00 00 00
CHG
08 88 12 BD 00 00 00 FF FF FF FF 00 00 AD FF 00 00 00 00 00 00
DEF
00 80 02 00 00
CHG
00 80 02 76 00
58
Barracuda 1 and 2 Product Manual, Rev. C
Table 7.
Mode sense data, ST11950 default values
(SCSI-2 implementation)
Bytes 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Mode
Sense 9F 00 10 08
Data 00 32 5F 77 00 00 02 00
<—————————Mode page headers and parameter data bytes—————————>
Mode
Page
DEF
01 81 0A 04 1B 30 00 00 00 03 00 FF FF
CHG
01 81 0A EF FF 00 00 00 00 FF 00 00 00
DEF
02 82 0E 80 80 00 0A 00 00 00 00 00 00 00 00 00 00
CHG
02 82 0E FF FF 00 00 00 00 00 00 00 00 80 00 00 00
DEF
03 83 16 00 0F 00 06 00 00 00 0F 00 51 02 00 00 01 00 07 00 10 40 00 00 00
CHG
03 83 16 FF FF FF FF 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00
DEF
04 84 16 00 0A 93 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1C 20 00 00
CHG
04 84 16 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 FF 00 00 00 00 00
DEF
07 87 0A 00 1B 30 00 00 00 00 00 FF FF
CHG
07 87 0A 0F FF 00 00 00 00 00 00 00 00
DEF
08 88 12 14 00 FF FF 00 00 00 9F 02 7C 80 03 00 00 00 00 00 00
CHG
08 88 12 BD 00 00 00 FF FF FF FF 00 00 A0 FF 00 00 00 00 00 00
DEF
0A 8A 0A 00 10 00 00 00 00 00 00 00 00
CHG
0A 8A 0A 01 01 00 00 00 00 00 00 00 00
DEF
0C 8C 16 80 00 00 18 00 00 00 00 00 00 00 0A 92 0E 00 00 00 00 00 00 10 00
CHG
0C 8C 16 40 00 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
DEF
00 80 02 00 00
CHG
00 80 02 76 00
Barracuda 1 and 2 Product Manual, Rev. C
Table 8.
59
Mode sense data, ST12550 default values
(SCSI-1 implementation)
Bytes 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Mode
Sense 64 00 10 08
Data 00 3F C3 B9 00 00 02 00
<—————————Mode page headers and parameter data bytes—————————>
Mode
Page
DEF
01 81 06 04 1B 30 00 00 FF
CHG
01 81 06 EF FF 00 00 00 00
DEF
02 82 0A 80 80 00 0A 00 00 00 00 00 00
CHG
02 82 0A FF FF 00 00 00 00 00 00 00 00
DEF
03 83 16 00 13 00 09 00 00 00 13 00 51 02 00 00 01 00 07 00 10 40 00 00 00
CHG
03 83 16 FF FF FF FF 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00
DEF
04 84 12 00 0A 94 13 00 00 00 00 00 00 00 00 00 00 00 00 00 00
CHG
04 84 12 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 FF 00
DEF
08 88 12 14 00 FF FF 00 00 00 9F 02 7C 80 03 00 00 00 00 00 00
CHG
08 88 12 BD 00 00 00 FF FF FF FF 00 00 A0 FF 00 00 00 00 00 00
DEF
00 80 02 00 00
CHG
00 80 02 76 00
60
Barracuda 1 and 2 Product Manual, Rev. C
Table 9.
Mode sense data, ST12550 default values
(SCSI-2 implementation)
Bytes 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Mode
Sense 9F 00 10 08
Data 00 3F C3 B9 00 00 02 00
<—————————Mode page headers and parameter data bytes—————————>
Mode
Page
DEF
01 81 0A 04 1B 30 00 00 00 03 00 FF FF
CHG
01 81 0A EF FF 00 00 00 00 FF 00 00 00
DEF
02 82 0E 80 80 00 0A 00 00 00 00 00 00 00 00 00 00
CHG
02 82 0E FF FF 00 00 00 00 00 00 00 00 80 00 00 00
DEF
03 83 16 00 13 00 09 00 00 00 13 00 51 02 00 00 01 00 07 00 10 40 00 00 00
CHG
03 83 16 FF FF FF FF 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00
DEF
04 84 16 00 0A 94 13 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1C 20 00 00
CHG
04 84 16 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 FF 00 00 00 00 00
DEF
07 87 0A 00 1B 30 00 00 00 00 00 FF FF
CHG
07 87 0A 0F FF 00 00 00 00 00 00 00 00
DEF
08 88 12 14 00 FF FF 00 00 00 9F 02 7C 80 03 00 00 00 00 00 00
CHG
08 88 12 BD 00 00 00 FF FF FF FF 00 00 A0 FF 00 00 00 00 00 00
DEF
0A 8A 0A 00 10 00 00 00 00 00 00 00 00
CHG
0A 8A 0A 01 01 00 00 00 00 00 00 00 00
DEF
0C 8C 16 80 00 00 18 00 00 00 00 00 00 00 0A 93 12 00 00 00 00 00 00 10 00
CHG
0C 8C 16 40 00 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
DEF
00 80 02 00 00
CHG
00 80 02 76 00
Barracuda 1 and 2 Product Manual, Rev. C
11.4
61
SCSI bus conditions
and miscellaneous features supported
Asynchronous SCSI bus conditions supported by the drive are listed in
Table 10. These conditions cause the SCSI device to perform certain
actions and can alter the phase sequence. Other miscellaneous operating
features supported are also listed here.
Table 10. SCSI bus conditions and other miscellaneous features
Condition/feature supported by:
SCSI-1 SCSI-2 Conditions or feature
N
N
Adaptive caching
Y
Y
Adaptive read lookahead
Y
Y
Arbitrating system
Y
Y
Asynchronous data transfer
N
Y
Asynchronous event notification
Y
Y
Attention condition
N
Y
Contingent allegiance condition
N
Y
Y
Y
Y
Y
Deferred error handling
Differential interface circuits available
Disconnect/reconnect
Y
Y
Parameter rounding (controlled by round bit
in Mode Select page 0)
N
Y
Queue tagging (up to 64 queue tags supported)
N
N
Y
Y
Reporting actual retry count in extended sense
bytes 15, 16, and 17
Reset condition
Y
Y
Y
Y
Y
Y
Y
Y
SMP = 1 in Mode Select command needed to save RPL
and rotational offset bytes (in Table 5.2.1-25 of the SCSI2 Interface Product Manual, Vol. 2)
Synchronous data transfer
Synchronized (locked) spindle operation
Segmented caching
N
N
Zero latency read
SCSI-1
Y
SCSI-2 Status supported
Y
Busy
Y
Y
Y
Y
Check condition
Condition met/good
Y
Y
Good
Y
Y
Y
Y
Intermediate/condition met/good
Intermediate/good
Y
Y
Reservation conflict
Y
Y
Queue full
62
11.5
Barracuda 1 and 2 Product Manual, Rev. C
Synchronous data transfer
The data transfer period to be used by the drive and the initiator is established
by an exchange of messages during the Message Phase of operation. See
the section on message protocol in the SCSI-2 Interface Product Manual.
11.5.1
Synchronous data transfer periods supported
Tables 11 and 12 list the synchronous data transfer periods supported by the
drives.
Table 11. Synchronous data transfer periods
for ST11950N/ND and ST12550N/ND drives
M
(decimal)
25
31
37
50
62
75
87
100
112
125
137
Transfer period
Transfer rate
(M times 4 nanoseconds) (mega transfers/second)
100
10.0
125
8.0
150
6.66
200
5.0
250
4.0
300
3.33
350
2.85
400
2.5
450
2.22
500
1.81
550
1.81
150
600
1.66
162
650
1.53
175
700
1.42
187
750
1.33
200
800
1.25
Table 12. Synchronous data transfer periods
for ST11950W/WD and ST12550W/WD drives
M
(decimal)
25
31
37
50
62
75
87
100
112
Transfer period
Transfer rate
(M times 4 nanoseconds) (mega transfers/second)
100
10.0
125
8.0
150
6.66
200
5.0
250
4.0
300
3.33
350
2.85
400
2.5
450
2.22
Barracuda 1 and 2 Product Manual, Rev. C
11.5.2
63
REQ/ACK offset
The maximum REQ/ACK offset supported by Barracuda 1 and 2 drives
is 15 (0Fh).
11.6
DC cable and connector
The drive receives DC power through a 4-pin connector mounted at the rear
of the main PCB (see Figure 23). Recommended part numbers of the mating
connector are listed below, but equivalent parts may be used.
Type of cable
14 AWG
Connector
AMP 1-480424-0
Contacts (20-14 AWG)
AMP 60619-4 (loose piece)
AMP 61117-4 (strip)
Note. The output of a power supply must meet SELV (safety extra low
voltage) as defined in IEC 950.
4
11.7
3 2
1
Pins
1
2
3
4
+12V DC
+12V DC return
+5V DC return
+5V DC
SCSI physical interface
Figures 23 and 24 illustrate the physical interface on Barracuda 1 and 2
drives. Locations of the DC power connector, the SCSI interface connector,
the I/O line terminators, and the drive select and option select headers are
shown.
Details of the physical, electrical, and logical characteristics are given below.
The SCSI operational aspects of Seagate drive interfaces are provided in the
SCSI-2 Interface Product Manual.
I/O Terminator Packs
(single-ended I/O only)
SCSI I/O
Connector
Pin 1 End
(of terminator)
Pin 1
J4
J01
DC Power Connector
Figure 23. ST11950N/ND and ST12550N/ND physical interface
64
Barracuda 1 and 2 Product Manual, Rev. C
SCSI I/O
Connector
Pin 1
J5
J4
J01
DC Power
Connector
Figure 24. ST11950W/WD and ST12550W/WD physical interface
11.7.1
Physical characteristics
This section defines the connectors, cables, signals, and terminators
needed to implement the SCSI interface.
11.7.1.1
Physical description
You can daisy chain multiple SCSI devices on a common cable if each
device has the same types of drivers and receivers (all single-ended or
all differential). Devices having single-ended interface circuits cannot
be on the same daisy chain with devices having a differential interface
circuit. All signals are common between SCSI devices. A maximum of
8 SCSI devices (including the host) may be daisy chained together
when using a non-wide bus and ST11950N/ND or ST12550N/ND drives.
A maximum of 16 SCSI devices (including the host) may be daisy
chained together when using a wide bus and ST11950W/WD or
ST12550W/WD drives.
Terminate both ends of the daisy chain, but do not terminate any intermediate
SCSI device. The single-ended (ST11950N, ST11950W, ST12550N, and
ST12550W) drives are equipped with permanently mounted IC terminators,
which you can turn on or off using the Enable SCSI Terminator jumper. See
Section 10.1 to locate the Enable SCSI Terminator jumper for each drive
model. The differential (ST11950ND, ST11950WD, ST12550ND, and
ST12550WD) drives do not have on-board terminators. You must provide
external termination to terminate a differential drive.
11.7.1.2
Cable requirements
Sections 11.7.1.2.1, 11.7.1.2.2, and 11.7.1.2.3 describe the single-ended,
differential, and general cable requirements for Barracuda 1 and 2 drives.
Barracuda 1 and 2 Product Manual, Rev. C
11.7.1.2.1
65
Single-ended I/O circuits (ST11950N, ST11950W,
ST12550N, and ST12550W drives)
The maximum total cable length for use with drives having single-endedI/O
driver and receiver circuits is 6 meters (19.7 feet) when operating at
transfer rates of 5 Mbytes/second or less, and 3 meters (9.85 feet) when
operating at transfer rates greater than 5 Mbytes/second (fast SCSI). A
stub length of no more than 0.1 meter (0.33 feet) is allowed off the mainline
interconnection with any connected equipment. An ideal impedance match
with cable terminators implies a cable characteristic impedance of 132
ohms. Single-ended I/O cable pin assignments for ST11950N and ST12550N
drives are shown in Table 13. Single-ended I/O cable pin assignments for
ST11950W and ST12550W drives are shown in Table 15.
11.7.1.2.2
Differential I/O circuits (ST11950ND, ST11950WD,
ST12550ND, and ST12550WD drives)
The maximum total cable length for use with drives having differential I/O
drivers and receiver circuits is 25 meters (82 feet). A stub length of no more
than 0.2 meter (0.66 foot) is allowed off the mainline interconnection with
any connected equipment. An ideal impedance match with cable terminators implies a cable characteristic impedance of 122 ohms. Differential I/O
cable pin assignments for ST11950ND and ST12550ND drives are shown
in Table 14. Differential I/O cable pin assignments for ST11950WD and
ST12550WD drives are shown in Table 16.
11.7.1.2.3
General cable characteristics
Note. Use only non-shielded cable connectors with ST11950N/ND and
ST12550N/ND drives. Use a 50-conductor flat cable or 25-conductor
twisted-pair cable. Use a minimum conductor size of 28 AWG to
minimize noise effects. The following non-shielded flat cables (or
equivalents) may be used:
Flat cable
35M-3365-50
Twisted-pair cable
Spectra twist in flat 455-248-50
In general, cables having the characteristic impedances given in Sections
11.7.1.2.1 and 11.7.1.2.2 are not available; however, impedances that are
lower are satisfactory. A characteristic impedance of 100 ohm +10% is
recommended for unshielded flat or twisted-pair ribbon cable. To minimize
discontinuities and signal reflections, cables of different impedances should
not be used in the same bus. Your specific setup may require tradeoffs in
shielding effectiveness, cable length, number of loads, transfer rates, and
cost to achieve satisfactory system operation. If shielded and unshielded
cables are mixed within the same SCSI bus, the effect of impedance
mismatch must be carefully considered. Proper impedance matching is
especially important to maintain adequate margin at fast SCSI transfer rates.
11.7.2
Connector requirements
ST11950N/ND and ST12550N/ND drives
Use a non-shielded 50-conductor cable connector consisting of two rows of
25 female contacts with adjacent centers 100 mils apart. The connector is
keyed (see Figure 27).
66
Barracuda 1 and 2 Product Manual, Rev. C
Recommended mating flat cable connector part numbers:
Closed end
3M-3425-7000
(for cable ends)
3M-3425-7050
Without strain relief,
no center key
With strain relief, no center key
Dupont-66900-290 With strain relief and center key
Open end
3M-3425-6000
(in daisy chain)
3M-3425-6050
Without strain relief,
no center key
With strain relief, no center key
Dupont-66900-250 With strain relief and center key
ST11950W/WD and ST12550W/WD drives
Recommended mating wide cable connector part numbers:
AMP 786096-7, female 68-pin
AMP 786090-7, male 68-pin
11.7.3
Electrical description
ST11950N, ST11950W, ST12550N, and ST12550W drives use singleended interface signals. These signals must be terminated with 110 ohm
active terminator circuits at each end of the total cable. Single-ended circuits
use open collector or three-state drivers. ST11950N, ST11950W, ST12550N,
and ST12550W drives can be configured to provide SCSI termination (see
Section 11.7.3.3).
ST11950ND, ST11950WD, ST12550ND and ST12550WD drives use differential interface signals. Each of these signals must be terminated at each end
of the total cable with 330 ohms to +5V and 330 ohms to ground with 150
ohms between each differential pair. All I/O circuits are open collector, threestate drivers. Differential I/O drives are shipped without terminators and have
no provisions for adding terminator sockets on the PCB. You must provide
external termination for these drives.
11.7.3.1
Single-ended drivers and receivers
Note. All single-ended terminators must be ANSI SCSI-2 alternative 2
active terminators.
Typical single-ended driver and receiver circuits for the Barracuda 1 and 2
family are shown in Figure 25. Use terminator circuits only when the disc
drive is first or last on the daisy chain. (See Note 1 following Figure 25.)
Transmitter characteristics
Single-ended drives use an ANSI SCSI compatible open-collector singleended driver. This driver is capable of sinking a current of 48 mA with a lowlevel output voltage of 0.4V.
Receiver characteristics
Single-ended drives use an ANSI SCSI single-ended receiver with hysteresis gate or equivalent as a line receiver.
Barracuda 1 and 2 Product Manual, Rev. C
67
Line Receiver
Line Driver
Transmitter
(or transceiver)
[4] +2.85V Receiver
[4] +2.85V
[1]
110
Ohm
Flat
Cable
Pair
[1]
110
Ohm
[3]
[2]
[2]
Figure 25. Single-ended transmitters and receivers
Notes:
[1] Part of active terminator circuits. Enable drive termination when it is first
or last on the daisy chain.
Interface signal levels and logical sense at the drive I/O connector are
defined as follows:
Logic level
Negated (0)
Asserted (1)
Driver output
≥ 2.5V : ≤ 5.25V
≤ 0.4V : ≥ 0.0V
Receiver input
≥ 2.0V : < 5.25V
≤ 0.8V : > 0.0V
The difference in the voltages between input and output signals is due to
losses in the cable.
[2] ANSI SCSI compatible circuits.
[3] Total interface cable length should not exceed that specified in Section
11.7.1.2.1.
[4] Source of drive terminator power is VR1 which has an input source
voltage selected by a jumper.
11.7.3.2
Differential drivers and receivers
Typical differential driver and receiver circuits used by ST11950ND,
ST11950WD, ST12550ND and ST12550WD drives are shown in Figure 26.
The differential drives have no provisions for terminator circuits.
Differential signals
All differential interface signals consist of two lines denoted +SIGNAL
and –SIGNAL. A signal is true when +SIGNAL is more positive than
–SIGNAL, and a signal is false when –SIGNAL is more positive than
+SIGNAL. Terminate all assigned signals at each end of the cable as
shown in Table 14. You must provide external termination for the differential
drives.
Output characteristics
Each signal driven by differential interface drives should have the following
output characteristics when measured at the disc drive’s SCSI connector:
Low-level output voltage*
= 2.0V maximum at low-level output current
= 55 milliamps
68
Barracuda 1 and 2 Product Manual, Rev. C
High-level output voltage*
= 3.0V minimum at high-level output current
= –55 milliamps
Differential voltage
= 1.0V minimum with common-mode voltage ranges
from –7V DC to +12V DC
* Measure these voltages between the output terminal and the SCSI
device’s logic ground reference.
The output characteristics must conform to EIA RS-485-1983.
Input characteristics
Each signal received by differential interface drives should have the following
input characteristics when measured at the disc drive’s SCSI connector:
Input current on either input
= +2.0 milliamps maximum
(includes both receivers and passive drivers)
This requirement is met with the input voltage varying between –7V DC and
+12V DC, with power on or off, and with the hysteresis equaling 35 mV
minimum.
The input characteristics must conform to EIA RS-485-1983.
+5V
+5V
5.6K
DE
Transmit/Receive
Enable
[1]
RE
LSI
XCVR
1
[3]
1
Transmit or
Receive
Signal [2]
R
[4]
2
Figure 26. Typical differential I/O line transmitters/receivers
and terminators
Notes:
[1] Positive logic enables transmitters (+5V = asserted).
Negative logic enables receivers (0V = asserted).
[2] Negative logic signal (0V = asserted).
[3] Total interface cable length should not exceed 82.1 feet (25 meters) from
the host to the end of the daisy chain.
[4] You must provide terminators.
Barracuda 1 and 2 Product Manual, Rev. C
11.7.3.3
69
Terminator requirements
ST11950N and ST12550N drives
Internal disc drive I/O termination consists of active circuits with resistor
modules that plug into sockets on the main PCB (see Figure 16). You may
order ST11950N and ST12550N drives with or without the resistor modules
installed to facilitate a particular application. All single initiator/single target
(non-daisy-chain) applications require you to terminate the initiator and disc
drive. Daisy-chain applications require you to terminate only the units at each
end of the daisy chain. All other peripherals on the chain should not be
terminated.
Note. Remove terminator resistor modules where terminators are not
required. Removal of terminator power source selection jumper (see
Figure 16) does not disconnect the terminator resistors from the
circuit.
For single-ended I/O Barracuda applications, the SCSI bus must be terminated at both ends with ANSI SCSI-2 alternative 2 termination (active
termination), especially if the bus will be operated at fast SCSI transfer rates.
Barracuda drives provide active termination as the on-board termination
option.
Note. All terminators used in the daisy chain must be active terminators as
described above.
ST11950W and ST12550W drives
Internal disc drive I/O termination consists of active circuits contained in
permanently mounted IC terminator packs on the main PCB (see Figure 18).
All single initiator/single target (non-daisy-chain) applications require you to
terminate the initiator and drive.
Daisy-chain configurations require you to terminate only the units at each
end of the daisy chain. Do not terminate any other peripheral on the chain.
Note. Remove the Enable Drive Terminator jumper on J4 pins 11 and 12
when terminators are not required.
ST11950ND, ST12550ND, ST11950WD, and ST12550WD drives
Differential I/O Barracuda drives do not have provisions to add terminator
sockets on the PCB. You must provide external termination.
11.7.3.4
Terminator power
You can configure terminator power in four different ways. See Section 10.1
for illustrations that show how to place jumpers enabling each of the following
terminator power configurations:
1. Drive accepts terminator power through SCSI bus pins
ST11950N and ST12550N
ST11950W and ST12550W
Pin 26
Pins 17, 18, 51, and 52
2. Drive supplies power to the SCSI bus.
3. Drive provides terminator power for optional internal terminator
resistors using the drive’s power connector.
4. Drive provides power to its own terminators and to the SCSI bus
terminator power line (pin 26).
70
Barracuda 1 and 2 Product Manual, Rev. C
SCSI devices providing terminator power (TERMPWR) must have the
following characteristics:
• V TERM = 4.50V to 5.25V
• 800 mA minimum source drive capability
• 1.0A maximum
ST11950ND, ST11950WD, ST12550ND and ST12550WD drives
You can configure terminator power only from the drive to the SCSI bus (see
Section 10.1).
11.8
SCSI non-wide physical interface
.60
(15.24)
.42 Ref.
(10.67)
.20 Typ.
(5.08)
.065 x 45° Chamfer Typ.
(1.65)
.26 Typ.
(6.60)
Pin 1
.037 Ref. Typ.
(.94)
3 2
4
1
CL
.100
(2.54)
.025
(.64)
.335 ± .010
(8.50)
+.001
.083 –.002 Dia.
Sq. Contact
(2.1)
Trifurcated Pin
(4 places)
50 Places
.16
(4.06)
.100 Typ.
(2.54)
"D" ± .010
.051
(1.30)
.045 Min. Typ.
(1.14)
"C" ± .010
3
.834 ± .010
(21.18)
.040 Ref.
(1.02)
"B" Ref.
"A" ± .010
.370 ± .010
(9.398)
No. Pos.
"A"
"B"
"C"
"D"
50
3.767
(95.68)
3.697
(93.90)
2.720
(69.09)
2.400
(60.96)
Figure 27. Non-shielded SCSI device connector
Barracuda 1 and 2 Product Manual, Rev. C
71
Table 13. Single-ended cable pin assignments
(non-shielded connector)
for ST11950N and ST12550N drives
Signal
Pin number
Signal
−DB (0)
2
−DB (1)
4
GROUND
30
−DB (2)
6
−ATN
32
−DB (3)
8
GROUND
34
−DB (4)
10
−BSY
36
−DB (5)
12
−ACK
38
−DB (6)
14
−RST
40
−DB (7)
16
−MSG
42
−DB (P)
18
−SEL
44
GROUND
20
−C/D
46
GROUND
22
−REQ
48
GROUND
24
−I/O
50
TERMPWR
26
GROUND
Pin number
28
Notes:
1. All odd pins except pin 25 are connected to ground. Pin 25 is left open.
Caution. Do not connect pin 25 to ground at the host end or the drive end
of the cable. If you accidentally plug in the I/O connector upside
down, terminator power on pin 26 will be shorted to ground.
2. The minus sign next to a signal indicates asserted state is the low voltage
of the two levels used for logic signals.
72
Barracuda 1 and 2 Product Manual, Rev. C
Table 14. Differential cable pin assignments
(non-shielded connector)
for ST11950ND and ST12550ND drives
1
2
− Signal name*
GROUND
DB (0)
3
4
−DB (0)
DB (1)
5
6
−DB (1)
DB (2)
7
8
−DB (2)
DB (3)
9
10
−DB (3)
DB (4)
11
12
−DB (4)
DB (5)
13
14
−DB (5)
DB (6)
15
16
−DB (6)
DB (7)
17
18
−DB (7)
DB (P)
19
20
DB (P)
DIFFSENS
21
22
GROUND
GROUND
23
24
GROUND
TERMPWR
25
26
TERMPWR
GROUND
27
28
GROUND
ATN
29
30
−ATN
+ Signal name*
SHIELD GND
Pin number
GROUND
31
32
GROUND
BSY
33
34
−BSY
ACK
35
36
−ACK
RST
37
38
−RST
MSG
39
40
−MSG
SEL
41
42
−SEL
C/D
43
44
−C/D
REQ
45
46
−REQ
I/O
47
48
−I/O
GROUND
49
50
GROUND
*See Section 11.7.3 for detailed electrical characteristics of these differential signals.
Barracuda 1 and 2 Product Manual, Rev. C
11.9
73
SCSI wide physical interface
1.368
(34.75)
.767
(19.46)
Position 1
68 Position SCSI Receptacle
AMPLIMITE .050 Series
.300
(7.62)
Position 1
.740
(18.8)
.870
(22.1)
12 Position Auxiliary
Shrouded Post Header
AMPMODU 2mm
.315
(8.00)
Position 1
4 Position Power
Header, Commercial
Mate-N-Lock
.403
(10.24)
.008 Typ
(.20)
Figure 28. Wide SCSI device connector
.010 Typ
(.25)
.033 Typ
(.84)
.015
(.38)
74
Barracuda 1 and 2 Product Manual, Rev. C
Table 15. Single-ended contact assignments (P cable)
for ST11950W and ST12550W drives
Signal
name
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
Connector
contact number
1
2
3
4
5
6
7
8
9
10
11
Connector
contact number
35
36
37
38
39
40
41
42
43
44
45
Signal
name
–DB (12)
–DB (13)
–DB (14)
–DB (15)
–DB (P1)
–DB (0)
–DB (1)
–DB (2)
–DB (3)
–DB (4)
–DB (5)
GROUND
GROUND
GROUND
GROUND
GROUND
TERMPWR
TERMPWR
RESERVED
GROUND
GROUND
GROUND
GROUND
GROUND
12
13
14
15
16
17
18
19
20
21
22
23
24
46
47
48
49
50
51
52
53
54
55
56
57
58
–DB (6)
–DB (7)
–DB (P)
GROUND
GROUND
TERMPWR
TERMPWR
RESERVED
GROUND
–ATN
GROUND
–BSY
–ACK
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
25
26
27
28
29
30
31
32
33
34
59
60
61
62
63
64
65
66
67
68
–RST
–MSG
–SEL
–C/D
–REQ
–I/O
–DB (8)
–DB (9)
–DB (10)
–DB (11)
Notes:
1. The hyphen preceding a signal name indicates that signal is active low.
2. Eight-bit devices that connect to the P cable should leave the following
signals open: –DB(8) –DB(9) –DB(10) –DB(11) –DB(12) –DB(13)–DB(14)
–DB(15) –DB(P1). All other signals should be connected as defined.
Barracuda 1 and 2 Product Manual, Rev. C
75
Table 16. Differential contact assignments (P cable)
for ST11950WD and ST12550WD drives
Signal
Connector
name
contact number
DB (12)
1
DB (13)
2
DB (14)
3
DB (15)
4
DB (P1)
5
GROUND
6
DB (0)
7
DB (1)
8
DB (2)
9
DB (3)
10
DB (4)
11
DB (5)
12
DB (6)
13
DB (7)
14
DB (P)
15
DIFFSENS
16
TERMPWR
17
TERMPWR
18
RESERVED
19
ATN
20
GROUND
21
BSY
22
ACK
23
RST
24
MSG
25
SEL
26
C/D
27
REQ
28
I/O
29
GROUND
30
DB (8)
31
DB (9)
32
DB (10)
33
DB (11)
34
Connector
contact number
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
Signal
name
–DB (12)
–DB (13)
–DB (14)
–DB (15)
–DB (P1)
GROUND
–DB (0)
–DB (1)
–DB (2)
–DB (3)
–DB (4)
–DB (5)
–DB (6)
–DB (7)
–DB (P)
GROUND
TERMPWR
TERMPWR
RESERVED
–ATN
GROUND
–BSY
–ACK
–RST
–MSG
–SEL
–C/D
–REQ
–I/O
GROUND
–DB (8)
–DB (9)
–DB (10)
–DB (11)
Notes:
1. The hyphen preceding a signal name indicates that signal is active low.
2. Eight-bit devices that connect to the P cable should leave the following
signals open: –DB(12) –DB(13) –DB(14) –DB(15) –DB(P1) –DB(8)
–DB(9) –DB(10) –DB(11) DB(12) DB(13) DB(14) DB(15) DB(P1) DB(8)
DB(9) DB(10) DB(11). All other signals should be connected as defined.
76
11.10
Barracuda 1 and 2 Product Manual, Rev. C
Disc drive SCSI timing
Table 17. Disc drive SCSI timing
Description
Target select time (no arbitration)
Target select time (with arbitration)
Target select to command
Target select to MSG out
Identify MSG to command
Command to status
Command to data (para. in)
Command to data (para. out)
Command to data (write to data buffer)
Command to disconnect MSG
Disconnect MSG to bus free
Disconnect to arbitration (for re-select)
This measures disconnected CMD overhead
Target win arbitration (for re-select)
Arbitration to re-select
Re-select to Identify MSG in
Re-select Identify MSG to status
Re-select Identify MSG to data (media)
Data to status
Status to command complete MSG
Command complete MSG to bus free
Data to save data pointer MSG
Save data pointer MSG to disconnect MSG
Command byte transfer
Next command byte access
Next CDB byte access (byte 2 of 6)
Next CDB byte access (byte 3 of 6)
Next CDB byte access (byte 4 of 6)
Next CDB byte access (byte 5 of 6)
Next CDB byte access (byte 6 of 6)
Next CDB byte access (byte 2 of 10)
Next CDB byte access (byte 3 of 10)
Next CDB byte access (byte 4 of 10)
Next CDB byte access (byte 5 of 10)
Next CDB byte access (byte 6 of 10)
Next CDB byte access (byte 7 of 10)
Next CDB byte access (byte 8 of 10)
Next CDB byte access (byte 9 of 10)
Next CDB byte access (byte 10 of 10)
continued
Waveform
symbol [1]
T00
T01
T02
T03
T04
T05
T06
T07
T08
T09
T10
T11
Waveform
table [1]
N/A
4.5-1,2
4.5-1
4.5-2
4.5-3
4.5-5
4.5-9
4.5-10
4.5-10
4.5-6
4.5-6,14
4.5-6
T12
T13
T14
T15
T16
T17
T18
T19
T20
T21
T22
4.5-7
4.5-7
4.5-7
4.5-8
4.5-11
4.5-15
4.5-5,8,15
4.5-5,8,15
4.5-14
4.5-14
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
4.5-4
T23.6.2
T23.6.3
T23.6.4
T23.6.5
T23.6.6
T23.10.2
T23.10.3
T23.10.4
T23.10.5
T23.10.6
T23.10.7
T23.10.8
T23.10.9
T23.10.10
Typical
Max
< 1 µs
< 250 µs
2.31 µs
2.36 µs
3.33 µs
3.34 µs
1.51 µs
1.54 µs
3.34 µs
3.36 µs
Command dependent
Command dependent
Command dependent
Command dependent
Command dependent
0.64 µs
0.68 µs
Command dependent
2.8 µs
1.8 µs
1.34 µs
Command dependent
Command dependent
Command dependent
1.0 µs
0.75 µs
4.5 µs
0.75 µs
0.04
0.55 µs
0.10 µs
0.09 µs
0.13 µs
0.13 µs
0.59 µs
0.14 µs
0.13 µs
0.12 µs
0.11 µs
0.10 µs
0.09 µs
0.13 µs
0.12 µs
0.56 µs
0.10 µs
0.10 µs
0.14 µs
0.14 µs
0.60 µs
0.14 µs
0.14 µs
0.12 µs
0.12 µs
0.10 µs
0.10 µs
0.14 µs
0.12 µs
Barracuda 1 and 2 Product Manual, Rev. C
77
continued from previous page
Description
Data in byte transfer (parameter)
Data out byte transfer (parameter)
Next data in byte access (parameter)
Next data out byte access (parameter)
Data in byte transfer (media) [2]
Data out byte transfer (media) [2]
Next data in byte access (media) [2]
Next data out byte access (media) [2]
MSG IN byte transfer
Waveform
symbol [1]
T24
T25
T26
T27
T28
T29
T30
T31
T32
MSG OUT byte transfer
STATUS byte transfer
T33
T34
Synchronous data transfer characteristics:
Request signal transfer period [3]
–
Waveform
table [1]
4.5-12
4.5-13
4.5-12
4.5-13
4.5-12
4.5-13
4.5-12
4.5-13
4.5-5,7
4.5-8,14,15
4.5-2
4.5-5,8
4.5-15
–
Typical
0.10 µs
0.10 µs
0.03 µs
0.03 µs
0.10 µs
0.10 µs
0.09 µs
Max
0.04 µs
0.04 µs
0.12 µs
0.12 µs
0.04 µs
0.04 µs
0.12 µs
0.12 µs
0.04 µs
0.04 µs
0.04 µs
various
800 ns
Notes:
[1] See the SCSI-2 Interface Product Manual (part number 77738479), Section 4.5.
[2] Maximum SCSI asynchronous interface transfer rate is given in Section 5.3.
[3] Synchronous transfer period is determined by negotiations between an initiator and a drive. The
drive is capable of setting periods as given in Section 11.5 in this manual. See also Sections
3.1.5.2 and 3.5.3.2 of the SCSI-2 Interface Product Manual for a description of synchronous
data transfer operation.
General timing diagrams for SCSI interface operation are shown in the SCSI-2 Interface Product
Manual, Section 4.5.
78
Barracuda 1 and 2 Product Manual, Rev. C
Barracuda 1 and 2 Product Manual, Rev. C
Index
Symbols
12V current profile 34
96-bit Reed-Solomon error correction code 7
A
AC power requirements 31
acoustics 37
active termination 69
active terminator circuits 66
actuator assembly 6
adapter accessory frame kit 8
adaptive read lookahead 16
air cleanliness requirements 37
air flow 22
altitude, effective limits 36
ambient temperature range 35
ANSI, documents 3
asynchronous
data transfer protocol 7
SCSI bus conditions supported 61
automatic
adaptive thermal compensation 11
shipping lock 6, 7
thermal compensation 7, 11
autowrite and read reallocation 7
B
Barracuda Installation Guide 8
bits per inch, number of 11
bytes
per sector, allowable range 7
per surface, number of 11
per track, number of 11
C
cable pin assignments
differential 72
single-ended 71
cable requirements 64
cache control 15
caching write data 16
capacities
79
formatted 8
unformatted 8
conducted noise immunity 33
contact assignments
differential (P cable) 75
single-ended (P cable) 74
cooling, mechanical 40
current requirements 31
D
data block size, modifying the 8
data buffer to/from disc media 14
data heads, number of 11
data transfer rate 14
data zone 6
DC
cable and connector 63
power requirements 31
defect and error management 43
defects and errors
ETF defect list 43
primary defect list 43
Delayed Motor Start option 49
diameter, media (disc) 41
differential
I/O, cable requirements 65
differential drivers/receivers 67
terminating 67
differential I/O
cable requirements 65
digital offset values 19
dimensions
N/ND J4 connector 51
W/WD J5 connector 51
disc rotation speed 11
disconnect/reconnect 5
drive
failure, defined 22
orientation 40
drivers and receivers 50
E
effective altitude (sea level)
electromagnetic
compatibility 37
interference (EMI) 21
36
80
Barracuda 1 and 2 Product Manual, Rev. C
EMC/regulatory requirements, meeting 3
Enable Drive Terminator 49
Enable Motor Start option 47, 49
environmental interference 21
environmental limits
effective altitude 36
shock and vibration 36
temperature 35
error correction code 7
error rates 21
internal data rate
F
K
fans, positioning for cooling 22
features
listed 7
firmware 7
flaw reallocation performance impact 14
flawed sector reallocation 7
format drive command execution time 13
formatting 9
front panel 8
KYHX temperature, measuring 27
G
grounding
52
H
head and disc assembly (HDA) 5
cooling 22
measuring the temperature of the 27
head switch, overhead time 14
heat/power dissipation 35
hot plugging Barracuda disc drives 28
humidity 35
HYHX temperature, measuring 25
I
index signal 18
inquiry data 56
installation 28
instructions 9
plug in and play 28
service tools 28
interface
physical 51
requirements 53
interleave 7
minimum sector 14
11
J
J01, jumper connector 47, 49
J2, jumper connector 47
J5
jumper connector 49
jumper connectors
explained 47, 49
JYHX temperature, measuring 26
L
landing zone 6
M
mean time between failures (MTBF) 22
mechanical specifications
depth 38
height 38
weight 38
width 38
media
characteristics 41
description 41
diameter 41
misc. operating features supported 61
miscorrected data transferred 21
Mode Select command 15
Mode Sense data 56
Motor Start command 14
MTBF 21
multiple initiators 5
N
noise
defined 33
maximum allowed 33
O
offset values 19
one track cylinder switch, overhead time
operating current 31, 32
option/configuration headers 45
14
Barracuda 1 and 2 Product Manual, Rev. C
P
panel, front 8
Parity Disable option 49
performance
general 7, 14
list of characteristics 11
physical
interface 51
rotational offsets 19
physical/electrical specifications 31
power
control switch 15
dissipation 6
requirements, AC and DC 31
prefetch/multi-segmented cache control
preventive maintenance 7, 21, 28
15
R
radiated emissions, characterizations 3
reallocation of defects
on command (post format) 7
recoverable error rate 21
Reed-Solomon error correction code 7
reference documents
Barracuda 1 and 2 Installation Guide 3, 8
SCSI-2 Reference Manual 3
reference index signal 50
termination 51
reference signal 18, 19
relative humidity
non-operating 35
operating 35
reliability
general characteristics 7
service, and 22
specifications 21
REQ/ACK offset 63
resistor modules 69
rotation speed 11
rotational
latency, average 11
position locking 18
skew, operating the drive with 19
S
safety agencies, certification 3
81
safety/regulatory agency compliance 3
SCSI
bus conditions and misc. features 61
drivers and receivers 7
SCSI interface
cable connector requirements 65
electrical description
differential drivers/receivers 66
single-ended drivers/receivers 66
messages supported by the 53
physical connections 63
terminator requirements 69
transfer rate 14
SCSI physical interface 63
non-wide 70
wide 73
SCSI timing 76
sector
reallocation scheme 7
size, allowable range 7, 14
seek
error rate 21
errors, defined 22
times, listed 13
seek errors 22
self-configuring host software 5
service
life 21, 28
philosophy 28
tools 28
servo heads, number of 11
shock
non-operating 36
operating
abnormal 36
normal 36
packaged 36
vibration, and 36
single-ended
drivers/receivers 66
I/O, cable requirements 65
SCSI drivers and receivers 7
single-ended I/O
cable requirements 65
single-unit shipping pack kit 8
spare reallocation scheme 8
spindle
82
brake 7
enabling and disabling 18
stopping with the Motor Start command 15
synchronization mode 18
start current 31, 32
start/stop time 14
synchronized
drive interconnect diagram 17
spindle operation 17
spindles interface 50
spindles interface, electrical description 50
synchronous
data transfer
periods supported 62
protocol 7
spindle 7
T
temperature, operating 35
terminating
differential drivers/receivers 66
SCSI devices 64
single-ended drivers/receivers 66
terminator
power 47, 49, 69
requirements 69
terminator power
options 47, 49
timing 76
tracks
per inch, number of 11
per surface, number of 11
U
UL 3
unit attention 18
unrecoverable
error, defined 21
write errors, defined 21
unrecovered data transferred 21
V
vibration
non-operating 37
operating
Barracuda 1 and 2 Product Manual, Rev. C
abnormal 37
normal 37
voltage requirements
31
W
write data, caching 16
write errors 21
WYGX temperature, measuring
Z
zone bit recording (ZBR)
7
24
Barracuda 1 and 2 Product Manual, Rev. C
83
Seagate Technology, Inc.
920 Disc Drive, Scotts Valley, California 95066-4544, USA
Publication Number: 83327780, Rev. C, Printed in USA